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 A081641 a(n) = n-th prime of class 13- according to the Erdős-Selfridge classification. 6
 36449279, 53065907, 59681213, 69096887, 132756479, 135388367, 164255999, 179043637, 188991053, 207290663, 241560239, 279709259, 309550999, 364492781, 372993983, 377982103, 398007431, 406165099, 425633717, 445901987, 447609067, 516737983 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES R. K. Guy, Unsolved Problems in Number Theory, A18. LINKS M. F. Hasler, Table of n, a(n) for n=1..1641 MATHEMATICA PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] - 1]]; ClassMinusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[23733333], ClassMinusNbr[ Prime[ # ]] == 12 &]] PROG (PARI) A081641 = nextclassminus(A081640) /* cf. A081640 */ - M. F. Hasler, Apr 05 2007 CROSSREFS Cf. A005113, A005105, A005106, A005107, A005108, A081633, A081633, A081635, A081636, A081637, A081638. Cf. A056637, A081640, A129248. Sequence in context: A254389 A254396 A253984 * A251372 A204852 A028965 Adjacent sequences:  A081638 A081639 A081640 * A081642 A081643 A081644 KEYWORD nonn AUTHOR Robert G. Wilson v, Mar 23 2003 EXTENSIONS Edited by N. J. A. Sloane, May 14 2008 at the suggestion of R. J. Mathar. STATUS approved

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Last modified August 17 11:22 EDT 2017. Contains 290635 sequences.