login
A174936
a(n) = Sum_{d|n} A007955(d) * A007955(n/d), where A007955(m) = product of divisors of m.
1
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
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
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Apr 02 2010
EXTENSIONS
Terms a(31) and beyond from Andrew Howroyd, Jan 05 2020
STATUS
approved