A037490 Base 5 digits are, in order, the first n terms of the periodic sequence with initial period 2,1.

2, 11, 57, 286, 1432, 7161, 35807, 179036, 895182, 4475911, 22379557, 111897786, 559488932, 2797444661, 13987223307, 69936116536, 349680582682, 1748402913411, 8742014567057, 43710072835286, 218550364176432, 1092751820882161

Offset

1,1

Links

Table of n, a(n) for n=1..22.

Index entries for linear recurrences with constant coefficients, signature (5,1,-5).

Formula

a(n) = 5a(n-1) + a(n-2) - 5a(n-3).

G.f.: x*(2+x) / ( (x-1)*(5*x-1)*(1+x) ). - R. J. Mathar, Nov 21 2011

a(n) = (11*5^n - 2*(-1)^n - 9)/24. - Stefano Spezia, Jul 21 2021

Mathematica

With[{nn=30}, Table[FromDigits[PadRight[{}, n, {2, 1}], 5], {n, nn}]] (* or *) LinearRecurrence[{5, 1, -5}, {2, 11, 57}, 30] (* Harvey P. Dale, Jun 13 2016 *)

Crossrefs

Sequence in context: A213098 A041129 A332524 * A037570 A240888 A120464

Adjacent sequences: A037487 A037488 A037489 * A037491 A037492 A037493

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved