A178188 a(n) = Sum_{k=1..n} 5^((k^2+3k)/2).

25, 3150, 1956275, 6105471900, 95373537112525, 7450675970460940650, 2910390496349340822268775, 5684344796471297836309816409400, 55511156915602623492479419714357425025

Offset

1,1

Comments

Series of the kind m^((k^2+3k)/2) from k=1 to n was studied by Bernoulli and Euler.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..50

Mathematica

aa = {}; m = 5; sum = 0; Do[sum = sum + m^((n + 3) n/2); AppendTo[aa, sum], {n, 1, 20}]; aa (*Artur Jasinski*)
Table[Sum[5^((k^2+3k)/2), {k, n}], {n, 10}] (* Harvey P. Dale, Jan 17 2015 *)

Prog

(PARI) a(n) = sum(k=1, n, 5^((k^2+3*k)/2)); \\ Michel Marcus, Sep 09 2013

Crossrefs

Cf. A178184-A178193.

Sequence in context: A226277 A013737 A018861 * A203186 A322249 A373878

Adjacent sequences: A178185 A178186 A178187 * A178189 A178190 A178191

Keyword

nonn

Author

Artur Jasinski, May 21 2010

Status

approved