A325818 - OEIS

A325818

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

1, 3, 4, 7, 6, 7, 8, 15, 13, 17, 12, 27, 14, 23, 22, 31, 18, 38, 20, 41, 32, 35, 24, 59, 31, 39, 40, 29, 30, 71, 32, 63, 46, 53, 48, 91, 38, 59, 56, 89, 42, 95, 44, 83, 76, 69, 48, 123, 57, 93, 70, 95, 54, 119, 72, 119, 80, 89, 60, 167, 62, 95, 104, 127, 84, 143, 68, 125, 94, 143, 72, 194, 74, 113, 124, 137, 96

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OFFSET

1,2

COMMENTS

a(n) is the largest k <= sigma(n) such that (-n + k) and (n-sigma(n))+k are coprime.

LINKS

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

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A000203(n) - A325817(n).

a(n) = n + A325826(n).

For all n: