Yellowstone sequence: Difference between revisions
added Tcl
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Line 995:
[1, 2, 3, 4, 9, 8, 15, 14, 5, 6, 25, 12, 35, 16, 7, 10, 21, 20, 27, 22, 39, 11, 13, 33, 26, 45, 28, 51, 32, 17]
</pre>
=={{header|Tcl}}==
<lang Tcl>proc gcd {a b} {
while {$b} {
lassign [list $b [expr {$a % $b}]] a b
}
return $a
}
proc gen_yellowstones {{maxN 30}} {
set r {}
for {set n 1} {$n <= $maxN} {incr n} {
if {$n <= 3} {
lappend r $n
} else {
## NB: list indices start at 0, not 1.
set pred [lindex $r end ] ;# a(n-1): coprime
set prepred [lindex $r end-1] ;# a(n-2): not coprime
for {set k 4} {1} {incr k} {
if {[lsearch -exact $r $k] >= 0} { continue }
if {1 != [gcd $k $pred ]} { continue }
if {1 == [gcd $k $prepred]} { continue }
## candidate k survived all tests...
break
}
lappend r $k
}
}
return $r
}
puts "The first 30 Yellowstone numbers are:"
puts [gen_yellowstones]</lang>
{{out}}
The first 30 Yellowstone numbers are:
1 2 3 4 9 8 15 14 5 6 25 12 35 16 7 10 21 20 27 22 39 11 13 33 26 45 28 51 32 17
=={{header|zkl}}==
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