

A047274


Numbers that are congruent to {0, 1} mod 7.


6



0, 1, 7, 8, 14, 15, 21, 22, 28, 29, 35, 36, 42, 43, 49, 50, 56, 57, 63, 64, 70, 71, 77, 78, 84, 85, 91, 92, 98, 99, 105, 106, 112, 113, 119, 120, 126, 127, 133, 134, 140, 141, 147, 148, 154, 155, 161, 162, 168, 169
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OFFSET

1,3


COMMENTS

Nonnegative k such that k or 6*k + 1 is divisible by 7.  Bruno Berselli, Feb 13 2018


LINKS

Table of n, a(n) for n=1..50.
Index entries for linear recurrences with constant coefficients, signature (1,1,1).


FORMULA

a(n) = 7*n  a(n1)  13 for n>1, a(1)=0.  Vincenzo Librandi, Aug 05 2010
From R. J. Mathar, Oct 08 2011: (Start)
a(n) = 7*n/2  19/4  5*(1)^n/4.
G.f.: x^2*(1 + 6*x) / ((1 + x)*(x  1)^2). (End)
a(n+1) = Sum_{k>=0} A030308(n,k)*A135092(k).  Philippe Deléham, Oct 17 2011


PROG

(PARI) forstep(n=0, 200, [1, 6], print1(n", ")) \\ Charles R Greathouse IV, Oct 17 2011


CROSSREFS

Sequence in context: A286261 A136037 A085334 * A037368 A281710 A037970
Adjacent sequences: A047271 A047272 A047273 * A047275 A047276 A047277


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane


STATUS

approved



