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A151973 Numbers n such that n^2 - n is divisible by 24. 4
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 (list; graph; refs; listen; history; text; internal format)
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: A003332 A091571 A225231 * A102219 A227650 A076093

Adjacent sequences:  A151970 A151971 A151972 * A151974 A151975 A151976

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Aug 23 2009

STATUS

approved

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Last modified January 22 12:13 EST 2019. Contains 319363 sequences. (Running on oeis4.)