A037572 Base 7 digits are, in order, the first n terms of the periodic sequence with initial period 2,1,2.

2, 15, 107, 751, 5258, 36808, 257658, 1803607, 12625251, 88376759, 618637314, 4330461200, 30313228402, 212192598815, 1485348191707, 10397437341951, 72782061393658, 509474429755608, 3566321008289258

Offset

1,1

Links

Table of n, a(n) for n=1..19.

Index entries for linear recurrences with constant coefficients, signature (7,0,1,-7).

Index entries for 7-automatic sequences.

Formula

G.f.: x*(2+x+2*x^2) / ( (x-1)*(7*x-1)*(1+x+x^2) ). - R. J. Mathar, Apr 27 2015

A007093(a(n)) = A037575(n).

Mathematica

Table[FromDigits[PadRight[{}, n, {2, 1, 2}], 7], {n, 20}] (* Harvey P. Dale, Dec 20 2024 *)

Prog

(PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -7, 1, 0, 7]^(n-1)*[2; 15; 107; 751])[1, 1] \\ Charles R Greathouse IV, Feb 13 2017

Crossrefs

Sequence in context: A308938 A037556 A037492 * A218686 A279087 A037740

Adjacent sequences: A037569 A037570 A037571 * A037573 A037574 A037575

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved