A130215 Order of modular group of degree 7^(n-1)+1.

0, 168, 58800, 20176632, 6920642400, 2373780746568, 814206798896400, 279272932041230232, 95790615690280324800, 32856181181767119892968, 11269670145346128902694000, 3865496859853722261079883832, 1325865422929826735882591047200, 454771840064930570410054065439368

Offset

1,2

References

E. Mathieu, Mémoire sur le nombre de valeurs que peut acquérir une fonction quand on y permute ses variables de toutes les manières possibles, Journ. de math. (2) 5 (1860), 9-42 (see p. 39).

Links

Table of n, a(n) for n=1..14.

Index entries for linear recurrences with constant coefficients, signature (350,-2401).

Formula

a(n) = (7^(n-1))*(7^(2n-2)-1)/2.

a(n) = 350*a(n-1)-2401*a(n-2). G.f.: 168*x^2 / ((7*x-1)*(343*x-1)). - Colin Barker, Sep 02 2013

Mathematica

Table[7^(x - 1) (7^(2 x - 2) - 1)/2, {x, 1, 15}]
LinearRecurrence[{350, -2401}, {0, 168}, 20] (* Harvey P. Dale, Aug 01 2022 *)

Crossrefs

Cf. A120689.

Sequence in context: A210815 A282375 A289327 * A275460 A364178 A275456

Adjacent sequences: A130212 A130213 A130214 * A130216 A130217 A130218

Keyword

nonn,easy

Author

Artur Jasinski, Aug 04 2007

Extensions

More terms from Colin Barker, Sep 02 2013

Status

approved