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- #!/usr/bin/ruby
- # Number of Lucas divisors of the n-th Lucas number
- # https://oeis.org/A356122
- func a(k) {
- return 2 if (k == 0)
- return 1 if (k == 1)
- var n = k.lucas
- var count = 0
- for k in (0..Inf) {
- var t = k.lucas
- if (t.divides(n)) {
- ++count
- }
- break if (t >= n)
- }
- return count
- }
- for n in (0..10) {
- say "#{n} #{a(n)}"
- }
- __END__
- # PARI/GP program:
- a(n) = if(n==1, return(1)); my(k=fibonacci(n+1)+fibonacci(n-1),c=0,x=2,y=1); while(x <= k, if(k%x == 0, c++); [x,y]=[y,x+y]); c;
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