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Zumkeller numbers: Difference between revisions
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81081 153153 171171 189189 207207 223839 243243 261261 279279 297297 351351 459459 513513 567567 621621 671517 729729 742203 783783 793611 812889 837837 891891 908523 960687 999999 1024947 1054053 1072071 1073709 1095633 1108107 1145529 1162161 1198197 1224531 1270269 1307691 1324323 1378377
</pre>
=={{header|Swift}}==
{{trans|Go}}
<lang swift>import Foundation
extension BinaryInteger {
@inlinable
public var isZumkeller: Bool {
let divs = factors(sorted: false)
let sum = divs.reduce(0, +)
guard sum & 1 != 1 else {
return false
}
guard self & 1 != 1 else {
let abundance = sum - 2*self
return abundance > 0 && abundance & 1 == 0
}
return isPartSum(divs: divs[...], sum: sum / 2)
}
@inlinable
public func factors(sorted: Bool = true) -> [Self] {
let maxN = Self(Double(self).squareRoot())
var res = Set<Self>()
for factor in stride(from: 1, through: maxN, by: 1) where self % factor == 0 {
res.insert(factor)
res.insert(self / factor)
}
return sorted ? res.sorted() : Array(res)
}
}
@usableFromInline
func isPartSum<T: BinaryInteger>(divs: ArraySlice<T>, sum: T) -> Bool {
let count = divs.count
guard sum != 0 else {
return true
}
guard count != 0 else {
return false
}
let last = divs.last!
if last > sum {
return isPartSum(divs: divs.dropLast(), sum: sum)
}
return isPartSum(divs: divs.dropLast(), sum: sum) || isPartSum(divs: divs.dropLast(), sum: sum - last)
}
let zums = (2...).lazy.filter({ $0.isZumkeller })
let oddZums = zums.filter({ $0 & 1 == 1 })
let oddZumsWithout5 = oddZums.filter({ String($0).last! != "5" })
print("First 220 zumkeller numbers are \(Array(zums.prefix(220)))")
print("First 40 odd zumkeller numbers are \(Array(oddZums.prefix(40)))")
print("First 40 odd zumkeller numbers that don't end in a 5 are: \(Array(oddZumsWithout5.prefix(40)))")</lang>
{{out}}
<pre>First 220 zumkeller numbers are: [6, 12, 20, 24, 28, 30, 40, 42, 48, 54, 56, 60, 66, 70, 78, 80, 84, 88, 90, 96, 102, 104, 108, 112, 114, 120, 126, 132, 138, 140, 150, 156, 160, 168, 174, 176, 180, 186, 192, 198, 204, 208, 210, 216, 220, 222, 224, 228, 234, 240, 246, 252, 258, 260, 264, 270, 272, 276, 280, 282, 294, 300, 304, 306, 308, 312, 318, 320, 330, 336, 340, 342, 348, 350, 352, 354, 360, 364, 366, 368, 372, 378, 380, 384, 390, 396, 402, 408, 414, 416, 420, 426, 432, 438, 440, 444, 448, 456, 460, 462, 464, 468, 474, 476, 480, 486, 490, 492, 496, 498, 500, 504, 510, 516, 520, 522, 528, 532, 534, 540, 544, 546, 550, 552, 558, 560, 564, 570, 572, 580, 582, 588, 594, 600, 606, 608, 612, 616, 618, 620, 624, 630, 636, 640, 642, 644, 650, 654, 660, 666, 672, 678, 680, 684, 690, 696, 700, 702, 704, 708, 714, 720, 726, 728, 732, 736, 740, 744, 750, 756, 760, 762, 768, 770, 780, 786, 792, 798, 804, 810, 812, 816, 820, 822, 828, 832, 834, 836, 840, 852, 858, 860, 864, 868, 870, 876, 880, 888, 894, 896, 906, 910, 912, 918, 920, 924, 928, 930, 936, 940, 942, 945, 948, 952, 960, 966, 972, 978, 980, 984]
First 40 odd zumkeller numbers are: [945, 1575, 2205, 2835, 3465, 4095, 4725, 5355, 5775, 5985, 6435, 6615, 6825, 7245, 7425, 7875, 8085, 8415, 8505, 8925, 9135, 9555, 9765, 10395, 11655, 12285, 12705, 12915, 13545, 14175, 14805, 15015, 15435, 16065, 16695, 17325, 17955, 18585, 19215, 19305]
First 40 odd zumkeller numbers that don't end in a 5 are: [81081, 153153, 171171, 189189, 207207, 223839, 243243, 261261, 279279, 297297, 351351, 459459, 513513, 567567, 621621, 671517, 729729, 742203, 783783, 793611, 812889, 837837, 891891, 908523, 960687, 999999, 1024947, 1054053, 1072071, 1073709, 1095633, 1108107, 1145529, 1162161, 1198197, 1224531, 1270269, 1307691, 1324323, 1378377]</pre>
=={{header|zkl}}==
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