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 A178248 a(n) = 12^n + 1. 14
 2, 13, 145, 1729, 20737, 248833, 2985985, 35831809, 429981697, 5159780353, 61917364225, 743008370689, 8916100448257, 106993205379073, 1283918464548865, 15407021574586369, 184884258895036417, 2218611106740436993 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Prime factors of a(n) are in the Cunningham Project. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 S. S. Wagstaff, Jr., The Cunningham Project. Index entries for linear recurrences with constant coefficients, signature (13,-12). FORMULA O.g.f.: (2 - 13 x)/(1 - 13 x + 12 x^2) = (2 - 13 x)/((1 - x)(1 - 12 x)). EXAMPLE a(3) = 12^3 + 1 = 1729. MATHEMATICA nmax = 17; 12^Range[0, nmax] + 1 LinearRecurrence[{13, -12}, {2, 13}, 20] (* Harvey P. Dale, Nov 02 2015 *) PROG (MAGMA) [12^n + 1: n in [0..20]]; // Vincenzo Librandi, May 02 2011 (PARI) vector(21, n, 12^(n-1)+1) \\ Charles R Greathouse IV, May 02 2011 CROSSREFS Cf. A001021, A024140, A016125, A000051, A034472, A052539, A034474, A062394, A034491, A062395, A062396, A062397, A007689, A063376, A063481, A074600 - A074624, A034524, A228081. Sequence in context: A003581 A129256 A046245 * A107699 A079330 A059367 Adjacent sequences:  A178245 A178246 A178247 * A178249 A178250 A178251 KEYWORD nonn,easy AUTHOR Stuart Clary, Dec 20 2010 STATUS approved

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Last modified October 23 16:46 EDT 2019. Contains 328373 sequences. (Running on oeis4.)