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 A014632 Odd pentagonal numbers. 4
 1, 5, 35, 51, 117, 145, 247, 287, 425, 477, 651, 715, 925, 1001, 1247, 1335, 1617, 1717, 2035, 2147, 2501, 2625, 3015, 3151, 3577, 3725, 4187, 4347, 4845, 5017, 5551, 5735, 6305, 6501, 7107, 7315, 7957, 8177, 8855, 9087, 9801, 10045, 10795, 11051, 11837 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (1, 2, -2, -1, 1). FORMULA a(n) = a(n-1) +2*a(n-2) -2*a(n-3) -a(n-4) +a(n-5). a(n) = 48+2*a(n-2)-a(n-4). - Ant King, Aug 16 2011 G.f.: (1+4*x+28*x^2+8*x^3+7*x^4)/((1+x)^2*(1-x)^3). - R. J. Mathar, Jul 25 2009 a(n) = (3*(-1)^n+12*n+1)*((-1)^n+4*n+1)/8. - Ant King, Aug 16 2011 MAPLE A014632:=n->(3*(-1)^n+12*n+1)*((-1)^n+4*n+1)/8: seq(A014632(n), n=0..100); # Wesley Ivan Hurt, Apr 28 2017 MATHEMATICA Select[Table[n (3 n - 1)/2, {n, 100}], OddQ]  (* Harvey P. Dale, Feb 03 2011 *) PROG (MAGMA) [1/8*(11+3*(-1)^(n+1)-12*(n+1))*(3+(-1)^(n+1)-4*(n+1)): n in [0..40]]; // Vincenzo Librandi, Aug 17 2011 CROSSREFS Cf. A000326. Sequence in context: A087675 A128044 A299529 * A117985 A115707 A117793 Adjacent sequences:  A014629 A014630 A014631 * A014633 A014634 A014635 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Patrick De Geest STATUS approved

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Last modified October 23 14:54 EDT 2019. Contains 328345 sequences. (Running on oeis4.)