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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
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
Sequence in context: A254389 A254396 A253984 * A251372 A204852 A345630
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 March 28 08:19 EDT 2024. Contains 371236 sequences. (Running on oeis4.)