A298654 - OEIS

A298654

Least number k such that the sum of the anti-divisors of k is equal to the sum of the anti-divisors of k+n.

8, 55, 26, 15, 43, 10, 89, 22, 20, 129, 118, 430, 43, 32, 39, 88, 174, 179, 35, 31, 45, 161, 53, 27, 228, 407, 122, 86, 90, 149, 87, 288, 46, 177, 283, 28, 117, 130, 222, 158, 200, 82, 68, 62, 383, 932, 32, 63, 120, 375, 1107, 67, 298, 110, 119, 352, 122, 277

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

a(1) = 8 because the sum of the anti-divisors of 8 is 8 and of 9 is 8 again;

a(2) = 55 because the sum of the anti-divisors of 55 is 74 and of 57 is 74 again.

MAPLE

with(numtheory): P:=proc(q) local a, b, i, j, k, n; for i from 0 to q do for n from 1 to q do

k:=0; j:=n; while j mod 2 <> 1 do k:=k+1; j:=j/2; od;

a:=sigma(2*n+1)+sigma(2*n-1)+sigma(n/2^k)*2^(k+1)-6*n-2;