A174938 a(n) = Sum_{k<=n} A007955(k) * A007955(n-k+1), where A007955(m) = product of divisors of m.

1, 4, 10, 28, 51, 140, 252, 452, 953, 1164, 2974, 5676, 13531, 14828, 40744, 27260, 146845, 55372, 288174, 177700, 574867, 204916, 3721652, 988332, 3550621, 3267452, 11129590, 4173196, 46286551, 7402156, 77215116, 27553508, 97906405, 20169220, 1259249286, 43886132

Offset

1,2

Links

Table of n, a(n) for n=1..36.

Example

For n = 4, A007955(n) = b(n): a(4) = b(1)*b(4) + b(2)*b(3) + b(3)* b(2) + b(4)*b(1) = 1*8 + 2*3 + 3*2 + 8*1 = 28.

Mathematica

s[n_] := n^(DivisorSigma[0, n]/2); a[n_] := Sum[s[k] * s[n-k+1], {k, 1, n}]; Array[a, 50] (* Amiram Eldar, Aug 06 2024 *)

Crossrefs

Cf. A007955.

Sequence in context: A222963 A333172 A257028 * A032248 A092504 A340568

Adjacent sequences: A174935 A174936 A174937 * A174939 A174940 A174941

Keyword

nonn

Author

Jaroslav Krizek, Apr 02 2010

Extensions

More terms from Amiram Eldar, Aug 06 2024

Status

approved