A326039 Largest square dividing the sum of divisors of n: a(n) = A008833(sigma(n)).

1, 1, 4, 1, 1, 4, 4, 1, 1, 9, 4, 4, 1, 4, 4, 1, 9, 1, 4, 1, 16, 36, 4, 4, 1, 1, 4, 4, 1, 36, 16, 9, 16, 9, 16, 1, 1, 4, 4, 9, 1, 16, 4, 4, 1, 36, 16, 4, 1, 1, 36, 49, 9, 4, 36, 4, 16, 9, 4, 4, 1, 16, 4, 1, 4, 144, 4, 9, 16, 144, 36, 1, 1, 1, 4, 4, 16, 4, 16, 1, 121, 9, 4, 16, 36, 4, 4, 36, 9, 9, 16, 4, 64, 144, 4, 36

Offset

1,3

Links

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

Index entries for sequences related to sigma(n)

Formula

a(n) = A008833(A000203(n)) = A326038(n)^2.

a(n) = A000203(n) - A326040(n).

Mathematica

Module[{sqs=Range[100, 1, -1]^2}, Table[SelectFirst[sqs, Divisible[ DivisorSigma[ 1, n], #]&], {n, 100}]] (* Harvey P. Dale, Jul 29 2019 *)

Prog

(PARI)
A008833(n) = (n/core(n));
A326039(n) = A008833(sigma(n));

Crossrefs

Cf. A000203, A008833, A326038, A326040.

Sequence in context: A106314 A152716 A298575 * A183374 A176263 A110812

Adjacent sequences: A326036 A326037 A326038 * A326040 A326041 A326042

Keyword

nonn

Author

Antti Karttunen, Jun 05 2019

Status

approved