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A151981 Numbers n such that n^2 - n is divisible by 48. 4
0, 1, 16, 33, 48, 49, 64, 81, 96, 97, 112, 129, 144, 145, 160, 177, 192, 193, 208, 225, 240, 241, 256, 273, 288, 289, 304, 321, 336, 337, 352, 369, 384, 385, 400, 417, 432, 433, 448, 465, 480, 481, 496, 513, 528, 529, 544, 561, 576, 577, 592, 609, 624, 625, 640, 657, 672 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Numbers congruent to {0, 1, 16, 33} mod 48. - Charles R Greathouse IV, Apr 10 2012

LINKS

Table of n, a(n) for n=1..57.

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

FORMULA

From Colin Barker, Apr 10 2012: (Start)

G.f.: x^2*(1+15*x+17*x^2+15*x^3)/((1-x)^2*(1+x)*(1+x^2)).

a(n) = a(n-1) + a(n-4) - a(n-5) for n>5. (End)

a(n) = 12*n-(35+3*i^(2*n))/2+(2+2*i)*i^(-n)+(2-2*i)*i^n where i=sqrt(-1). - Wesley Ivan Hurt, Jun 07 2016

MAPLE

A151981:=n->12*n-(35+3*I^(2*n))/2+(2+2*I)*I^(-n)+(2-2*I)*I^n: seq(A151981(n), n=1..100); # Wesley Ivan Hurt, Jun 07 2016

MATHEMATICA

Table[12n-(35+3*I^(2*n))/2+(2+2*I)*I^(-n)+(2-2*I)*I^n, {n, 80}] (* Wesley Ivan Hurt, Jun 07 2016 *)

PROG

(PARI) a(n)=n\4*48+[-15, 0, 1, 16][n%4+1] \\ Charles R Greathouse IV, Apr 10 2012

(MAGMA) [n : n in [0..800] | n mod 48 in [0, 1, 16, 33]]; // Wesley Ivan Hurt, Jun 07 2016

CROSSREFS

Sequence in context: A119349 A070591 A181452 * A110472 A110502 A095784

Adjacent sequences:  A151978 A151979 A151980 * A151982 A151983 A151984

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Aug 23 2009

STATUS

approved

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Last modified January 15 19:04 EST 2019. Contains 319170 sequences. (Running on oeis4.)