A262716 a(n) = 31^(2*n+1).

31, 29791, 28629151, 27512614111, 26439622160671, 25408476896404831, 24417546297445042591, 23465261991844685929951, 22550116774162743178682911, 21670662219970396194714277471, 20825506393391550743120420649631, 20013311644049280264138724244295391

Offset

0,1

Comments

31*a(n) is a square.

In general, Sum_{i>=0} 1/m^(2*i+1) = m/(m^2-1) when |m|>1. In this case, Sum_{i>=0} 1/a(i) = 31/960. [Bruno Berselli, Oct 07 2015]

Links

G. C. Greubel, Table of n, a(n) for n = 0..250

Index entries for linear recurrences with constant coefficients, signature (961).

Formula

G.f.: 31/(1 - 961*x).

a(n) = 961*a(n-1).

Mathematica

31^Range[1, 30, 2]

Prog

(Magma) [31^(2*n+1): n in [0..15]];
(PARI) Vec(31/(1 - 961*x) + O(x^30)) \\ Michel Marcus, Oct 07 2015
(PARI) vector(15, n, n--; 31^(2*n+1)) \\ Bruno Berselli, Oct 07 2015
(Sage) [31^(2*n+1) for n in (0..15)] # Bruno Berselli, Oct 07 2015

Crossrefs

Second bisection of A009975 (powers of 31).

Cf. similar sequences listed in A262715.

Sequence in context: A239167 A263585 A176349 * A033176 A263163 A188956

Adjacent sequences: A262713 A262714 A262715 * A262717 A262718 A262719

Keyword

nonn,easy

Author

Vincenzo Librandi, Oct 07 2015

Status

approved