A364387 Number of divisors of n of the form 4*k+3 that are at most sqrt(n).

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1

Offset

1,63

Links

Table of n, a(n) for n=1..99.

Formula

G.f.: Sum_{k>=0} x^(4*k+3)^2 / (1 - x^(4*k+3)).

Mathematica

Table[Count[Divisors[n], _?(# <= Sqrt[n] && MemberQ[{3}, Mod[#, 4]] &)], {n, 99}]
nmax = 99; CoefficientList[Series[Sum[x^(4 k + 3)^2/(1 - x^(4 k + 3)), {k, 0, nmax}], {x, 0, nmax}], x] // Rest

Crossrefs

Cf. A001842, A038548, A364358.

Sequence in context: A112607 A161371 A327928 * A147645 A091970 A093955

Adjacent sequences: A364384 A364385 A364386 * A364388 A364389 A364390

Keyword

nonn

Author

Ilya Gutkovskiy, Jul 21 2023

Status

approved