A178189 Numerators of sum (1/5)^((k^2+3k)/2) from k=1 to n.

1, 126, 78751, 246096876, 3845263687501, 300411225586015626, 117348134994537353906251, 229195576161205769348146484376, 2238238048449275091290493011484375001

Offset

1,2

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 = 1/5; sum = 0; Do[sum = sum + m^((n + 3) n/2); AppendTo[aa, Numerator[sum]], {n, 1, 20}]; aa (*Artur Jasinski*)

Prog

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

Crossrefs

Cf. A178184-A178193.

Sequence in context: A364402 A295816 A213405 * A365026 A294852 A078206

Adjacent sequences: A178186 A178187 A178188 * A178190 A178191 A178192

Keyword

nonn,frac

Author

Artur Jasinski, May 21 2010

Status

approved