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 A143988 Numbers congruent to {5, 13} mod 18. 1
 5, 13, 23, 31, 41, 49, 59, 67, 77, 85, 95, 103, 113, 121, 131, 139, 149, 157, 167, 175, 185, 193, 203, 211, 221, 229, 239, 247, 257, 265, 275, 283, 293, 301, 311, 319, 329, 337, 347, 355, 365, 373, 383, 391, 401, 409, 419, 427, 437, 445, 455, 463, 473, 481 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..10000 Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA a(n) = 18*(n-1) - a(n-1) for n > 1 and a(1)=5. - Vincenzo Librandi, Nov 25 2010 From Colin Barker, Oct 25 2019: (Start) G.f.: x*(5 + 8*x + 5*x^2) / ((1 - x)^2*(1 + x)). a(n) = a(n-1) + a(n-2) - a(n-3) for n>3. a(n) = ((-1)^(1+n) + 18*n - 9) / 2. (End) MATHEMATICA Select[Range@ 500, MemberQ[{5, 13}, Mod[#, 18]] &] (* Michael De Vlieger, Nov 23 2018 *) PROG (GAP) Filtered([1..500], k->k mod 18 = 5 or k mod 18 = 13); # Muniru A Asiru, Nov 24 2018 (PARI) Vec(x*(5 + 8*x + 5*x^2) / ((1 - x)^2*(1 + x)) + O(x^60)) \\ Colin Barker, Oct 25 2019 CROSSREFS Sequence in context: A155142 A155552 A219546 * A129806 A125830 A049882 Adjacent sequences:  A143985 A143986 A143987 * A143989 A143990 A143991 KEYWORD nonn,easy AUTHOR Giovanni Teofilatto, Sep 07 2008 EXTENSIONS Corrected (213 replaced with 211, 231 with 229, 249 with 247, 265 with 267 etc.) by R. J. Mathar, Apr 22 2010 STATUS approved

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Last modified June 19 16:01 EDT 2021. Contains 345144 sequences. (Running on oeis4.)