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URL: https://oeis.org/A385451

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A385451
Least integer k such that the sum of its anti-divisors is equal to k + n.
1
5, 11, 14, 7, 10, 71, 13, 101, 48, 129, 18, 17, 46, 37, 22, 27, 62, 35, 28, 55, 66, 3279, 92, 49, 42, 155, 32, 1721, 154, 81, 50, 59, 38, 229, 152, 53, 222, 859, 58, 393, 190, 45, 52, 73, 68, 97, 104, 60, 128, 63, 72, 87, 436, 401, 136, 673, 142, 429, 272, 163
OFFSET
0,1
EXAMPLE
a(0) = 5: anti-divisors are 2, 3 and 2 + 3 - 5 = 0;
a(1) = 11: anti-divisors are 2, 3, 7 and 2 + 3 + 7 - 11 = 1;
a(2) = 14: anti-divisors are 3, 4, 9 and 3 + 4 + 9 - 14 = 2;
a(3) = 7: anti-divisors are 2, 3, 5 and 2 + 3 + 5 - 7 = 3.
MAPLE
with(numtheory): P:=proc(q, h) local a, b, j, k, n, v; v:=array(1..h);
for k from 1 to h do v[k]:=0; od; 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;
if a>=n then b:=a-n+1; if b<=h then if v[b]=0 then v[b]:=n; fi; fi; fi; od; op(v); end:
P(3300, 60);
CROSSREFS
Sequence in context: A073615 A346147 A275118 * A275640 A275805 A340605
KEYWORD
nonn,easy
AUTHOR
Paolo P. Lava, Jun 29 2025
STATUS
approved