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 A016778 a(n) = (3*n+1)^2. 11
 1, 16, 49, 100, 169, 256, 361, 484, 625, 784, 961, 1156, 1369, 1600, 1849, 2116, 2401, 2704, 3025, 3364, 3721, 4096, 4489, 4900, 5329, 5776, 6241, 6724, 7225, 7744, 8281, 8836, 9409, 10000, 10609, 11236 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS From Paul Curtz, Mar 28 2019: (Start) Sequence is a spoke of the hexagonal spiral built from the terms of A016777: .         \        100--97--94--91           \           \           49--46--43  88           / \       \   \         52  16--13  40  85         /   / \   \   \   \       55  19   1  10  37  82       /   /   /   /   /   /     58  22   4---7  34  79       \   \         /   /       61  25--28--31  76         \             /         64--67--70--73 (End) LINKS Shawn A. Broyles, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (3, -3, 1). FORMULA a(n) = a(n-1) + 3*(6*n-1); a(0)=1. - Vincenzo Librandi, Nov 20 2010 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); a(0)=1, a(1)=16, a(2)=49. - Harvey P. Dale, Mar 03 2013 a(n) = A247792(n) + 6*n. - Miquel Cerda, Oct 23 2016 G.f.: (1 + 13*x + 4*x^2)/(1 - x)^3. - Ilya Gutkovskiy, Oct 23 2016 a(n) = A000212(3*n) + A000212(1+3*n) + A000212(2+3*n). - Paul Curtz, Mar 28 2019 MATHEMATICA (3*Range[0, 50]+1)^2 (* or *) LinearRecurrence[{3, -3, 1}, {1, 16, 49}, 50] (* Harvey P. Dale, Mar 03 2013 *) PROG (Maxima) A016778(n):=(3*n+1)^2\$ makelist(A016778(n), n, 0, 20); /* Martin Ettl, Nov 12 2012 */ (PARI) a(n)=(3*n+1)^2 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A016777, A016779, A016780, A016781, A214550. Cf. A000212. Sequence in context: A231526 A041496 A059207 * A009952 A105823 A112630 Adjacent sequences:  A016775 A016776 A016777 * A016779 A016780 A016781 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified April 20 22:22 EDT 2019. Contains 322310 sequences. (Running on oeis4.)