A174936 a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m.

1, 4, 6, 20, 10, 84, 14, 160, 63, 220, 22, 3648, 26, 420, 480, 2368, 34, 11988, 38, 16480, 924, 1012, 46, 671424, 275, 1404, 1620, 44800, 58, 1621860, 62, 70656, 2244, 2380, 2520, 20190816, 74, 2964, 3120, 5154240, 82, 6226836, 86, 172480, 183870, 4324, 94, 510973440, 735, 251500

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..1000

Example

For n = 4, A007955(n) = b(n): a(4) = b(1)*b(4/1) + b(2)*b(4/2) + b(4)*b(4/4) = 1*8 + 2*2 + 8*1 = 20.

Prog

(PARI) a(n)={sumdiv(n, d, vecprod(divisors(d))*vecprod(divisors(n/d)))} \\ Andrew Howroyd, Jan 05 2020
(Magma) [&+[&*Divisors(d)*&*Divisors(n div d):d in Divisors(n)]:n in [1..50]]; // Marius A. Burtea, Jan 05 2020

Crossrefs

Cf. A007955.

Sequence in context: A013126 A012969 A057789 * A360823 A367864 A354204

Adjacent sequences: A174933 A174934 A174935 * A174937 A174938 A174939

Keyword

nonn

Author

Jaroslav Krizek, Apr 02 2010

Extensions

Terms a(31) and beyond from Andrew Howroyd, Jan 05 2020

Status

approved