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 A060641 Surround numbers of a length 2n zig-zag. 1
 161, 257, 373, 509, 665, 841, 1037, 1253, 1489, 1745, 2021, 2317, 2633, 2969, 3325, 3701, 4097, 4513, 4949, 5405, 5881, 6377, 6893, 7429, 7985, 8561, 9157, 9773, 10409, 11065, 11741, 12437, 13153, 13889, 14645, 15421, 16217, 17033 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Harry J. Smith, Table of n, a(n) for n = 2..1000 E. J. Friedman, Math. Magic Index entries for linear recurrences with constant coefficients, signature (3, -3, 1). FORMULA a(n) = 10n^2 + 46n + 29 with n > 1. From Colin Barker, Apr 22 2012: (Start) a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). G.f.: x^2*(161 - 226*x + 85*x^2)/(1-x)^3. (End) MATHEMATICA LinearRecurrence[{3, -3, 1}, {161, 257, 373}, 40] (* or *) Table[10x^2+66x+85, {x, 40}] (* Harvey P. Dale, May 26 2013 *) PROG (PARI) a(n)={10*n^2 + 46*n + 29} \\ Harry J. Smith, Jul 09 2009 CROSSREFS Cf. A047875, A000105, A060633. Sequence in context: A189639 A298615 A250644 * A209282 A340241 A157954 Adjacent sequences:  A060638 A060639 A060640 * A060642 A060643 A060644 KEYWORD nonn,easy AUTHOR Jason Earls, Apr 16 2001 STATUS approved

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Last modified January 23 01:37 EST 2021. Contains 340384 sequences. (Running on oeis4.)