A151973 Numbers n such that n^2 - n is divisible by 24.

0, 1, 9, 16, 24, 25, 33, 40, 48, 49, 57, 64, 72, 73, 81, 88, 96, 97, 105, 112, 120, 121, 129, 136, 144, 145, 153, 160, 168, 169, 177, 184, 192, 193, 201, 208, 216, 217, 225, 232, 240, 241, 249, 256, 264, 265, 273, 280, 288, 289, 297, 304, 312, 313, 321, 328, 336, 337, 345

Offset

1,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

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

Formula

a(n) = a(n-1)+a(n-4)-a(n-5) for n>5. G.f.: x^2*(8*x^3+7*x^2+8*x+1) / ((x-1)^2*(x+1)*(x^2+1)). - Colin Barker, Nov 29 2012

a(n) = (12*n+3*i^(n*(n-1))-2*(-1)^n-17)/2, where i=sqrt(-1). - Bruno Berselli, Nov 29 2012

Maple

A151973:=n->(12*n+3*I^(n*(n-1))-2*I^(2*n)-17)/2: seq(A151973(n), n=1..100); # Wesley Ivan Hurt, Jun 07 2016

Mathematica

CoefficientList[Series[x (8 x^3 + 7 x^2 + 8 x + 1) / ((x - 1)^2 (x + 1) (x^2 + 1)), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 19 2013 *)

Prog

(Magma) [n: n in [0..350] | IsZero(n*(n-1) mod 24)]; // Bruno Berselli, Nov 29 2012
(PARI) is(n)=(n^2-n)%24==0 \\ Charles R Greathouse IV, Oct 16 2015

Crossrefs

Sequence in context: A345793 A091571 A225231 * A102219 A227650 A339859

Adjacent sequences: A151970 A151971 A151972 * A151974 A151975 A151976

Keyword

nonn,easy

Author

N. J. A. Sloane, Aug 23 2009

Status

approved