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 A092464 Numbers n congruent to 4 or 9 mod 13. 2
 4, 9, 17, 22, 30, 35, 43, 48, 56, 61, 69, 74, 82, 87, 95, 100, 108, 113, 121, 126, 134, 139, 147, 152, 160, 165, 173, 178, 186, 191, 199, 204, 212, 217, 225, 230, 238, 243, 251, 256, 264, 269, 277, 282, 290, 295, 303, 308, 316, 321, 329, 334, 342, 347, 355, 360 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n such that n^2 is congruent to 3 (modulo 13). LINKS FORMULA From R. J. Mathar, Apr 20 2009: (Start) a(n) = a(n-2) + 13 = a(n-1) + a(n-2) - a(n-3) = 13*n/2 - 13/4 - 3*(-1)^n/4. G.f.: x*(4+5*x+4*x^2)/((1+x)*(x-1)^2). (End) a(n) = 13*(n-1) - a(n-1), (with a(1)=4). - Vincenzo Librandi, Nov 17 2010 MATHEMATICA Select[Range[400], MemberQ[{4, 9}, Mod[#, 13]]&] (* or *) Select[Range[400], PowerMod[#, 2, 13]==3&](* Harvey P. Dale, Mar 05 2012 *) CROSSREFS A127547 is a subsequence. Sequence in context: A313355 A313356 A295494 * A173562 A161320 A170879 Adjacent sequences:  A092461 A092462 A092463 * A092465 A092466 A092467 KEYWORD nonn AUTHOR Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), Mar 25 2004 EXTENSIONS More terms from Ray Chandler, Mar 27 2004 Edited by N. J. A. Sloane, May 10 2007 Incorrect formula deleted by N. J. A. Sloane, Jun 16 2010 STATUS approved

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Last modified May 26 22:57 EDT 2019. Contains 323597 sequences. (Running on oeis4.)