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A174938
a(n) = Sum_{k<=n} A007955(k) * A007955(n-k+1), where A007955(m) = product of divisors of m.
0
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
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
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Apr 02 2010
EXTENSIONS
More terms from Amiram Eldar, Aug 06 2024
STATUS
approved