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Sum of primes in odd positions is prime: Difference between revisions
Sum of primes in odd positions is prime (view source)
Revision as of 16:23, 1 September 2021
, 2 years ago→{{header|Nim}}
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143 823 26,879
</pre>
=={{header|Nim}}==
<lang Nim>import strformat
template isOdd(n: Natural): bool = (n and 1) != 0
template isEven(n: Natural): bool = (n and 1) == 0
func isPrime(n: Positive): bool =
if n == 1: return false
if n.isEven: return n == 2
if n mod 3 == 0: return n == 3
var d = 5
while d * d <= n:
if n mod d == 0: return false
inc d, 2
if n mod d == 0: return false
inc d, 4
result = true
# Compute the sums of primes at odd position.
echo " i p(i) sum"
var idx = 0
var sum = 0
var p = 1
while p < 1000:
inc p
if p.isPrime:
inc idx
if idx.isOdd:
inc sum, p
if sum.isPrime:
echo &"{idx:3} {p:3} {sum:5}"</lang>
{{out}}
<pre> i p(i) sum
1 2 2
3 5 7
11 31 89
27 103 659
35 149 1181
67 331 5021
91 467 9923
95 499 10909
99 523 11941
119 653 17959
143 823 26879</pre>
=={{header|Raku}}==
<lang perl6>my @odd = grep { ++$ !%% 2 }, grep &is-prime, 2 ..^ 1000;
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