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 A195025 a(n) = n*(14*n + 3). 7
 0, 17, 62, 135, 236, 365, 522, 707, 920, 1161, 1430, 1727, 2052, 2405, 2786, 3195, 3632, 4097, 4590, 5111, 5660, 6237, 6842, 7475, 8136, 8825, 9542, 10287, 11060, 11861, 12690, 13547, 14432, 15345, 16286, 17255, 18252, 19277, 20330, 21411, 22520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Sequence found by reading the line from 0, in the direction 0, 17, ..., in the Pythagorean spiral whose edges have length A195019 and whose vertices are the numbers A195020. This is the one of the semi-axis of the square spiral, which is related to the primitive Pythagorean triple [3, 4, 5]. a(k) is a square for k=(3/56)*((449+120*sqrt(14))^n+(449-120*sqrt(14))^n-2). - Bruno Berselli, Oct 18 2011 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA a(n) =  14*n^2 + 3*n. G.f.: x*(17+11*x)/(1-x)^3. - Bruno Berselli, Oct 18 2011 PROG (MAGMA) [14*n^2 +3*n: n in [0..50]]; // Vincenzo Librandi, Oct 14 2011 (PARI) a(n)=n*(14*n+3) \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A144555, A152760, A185019, A195019, A195020, A195023, A195024, A193053, A195320. Sequence in context: A211593 A211587 A226026 * A010005 A172076 A063522 Adjacent sequences:  A195022 A195023 A195024 * A195026 A195027 A195028 KEYWORD nonn,easy AUTHOR Omar E. Pol, Oct 13 2011 EXTENSIONS Name suggested by Bruno Berselli, Oct 13 2011 STATUS approved

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Last modified July 31 04:27 EDT 2021. Contains 346367 sequences. (Running on oeis4.)