A069078 a(n) = n*(4*n^4 + 1).

0, 5, 130, 975, 4100, 12505, 31110, 67235, 131080, 236205, 400010, 644215, 995340, 1485185, 2151310, 3037515, 4194320, 5679445, 7558290, 9904415, 12800020, 16336425, 20614550, 25745395, 31850520, 39062525, 47525530, 57395655, 68841500, 82044625, 97200030, 114516635

Offset: 0

Author

Benoit Cloitre, Apr 05 2002

Keywords

• easy
• nonn

References

• Konrad Knopp, Theory and application of infinite series, Dover, p. 268

Links

• Konrad Knopp, Theorie und Anwendung der unendlichen Reihen, Berlin, J. Springer, 1922. (Original German edition of "Theory and Application of Infinite Series")

Crossrefs

Cf. A187832.

Programs

Mathematica

a[n_] := n*(4*n^4 + 1); Array[a, 40, 0] (* Amiram Eldar, Mar 08 2022 *)

Formula

Sum_{n>=1} (-1)^(n+1)/a(n) = log(2) - 1/2 (A187832). [Corrected by Amiram Eldar, Mar 08 2022]