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

Author

Jaroslav Krizek, Apr 02 2010

Keywords

• nonn

Examples

			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.
		

Links

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

Crossrefs

Cf. A007955.

Programs

Magma

[&+[&*Divisors(d)*&*Divisors(n div d):d in Divisors(n)]:n in [1..50]]; // Marius A. Burtea, Jan 05 2020

PARI

a(n)={sumdiv(n, d, vecprod(divisors(d))*vecprod(divisors(n/d)))} \\ Andrew Howroyd, Jan 05 2020

Extensions

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