A325972 a(n) is the largest k <= sigma(n)-A007947(n) such that n-k and n-(sigma(n)-k) are relatively prime.

0, 1, 0, 5, 0, 5, 0, 13, 10, 7, 0, 21, 0, 9, 8, 29, 0, 32, 0, 31, 10, 13, 0, 53, 26, 15, 36, 29, 0, 41, 0, 61, 14, 19, 12, 85, 0, 21, 16, 79, 0, 53, 0, 61, 62, 25, 0, 117, 50, 83, 20, 71, 0, 113, 16, 105, 22, 31, 0, 137, 0, 33, 82, 125, 18, 77, 0, 91, 26, 73, 0, 188, 0, 39, 108, 101, 18, 89, 0, 175, 118, 43, 0, 181, 22

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537

Index entries for sequences related to sigma(n)

Formula

a(n) = A000203(n) - A325971(n).

Prog

(PARI)
A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947
A325972(n) = { my(s=sigma(n)); forstep(i=s-A007947(n), 0, -1, if(1==gcd(n-i, n-(s-i)), return(i))); };

Crossrefs

Cf. A000203, A007947, A324213, A325818, A325962, A325966, A325970, A325971.

Sequence in context: A071873 A036478 A059628 * A073441 A202325 A337084

Adjacent sequences: A325969 A325970 A325971 * A325973 A325974 A325975

Keyword

nonn

Author

Antti Karttunen, May 31 2019

Status

approved