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A098168 Prime index j such that prime(j) = the n-th fortunate number, A005235(n). 1
2, 3, 4, 6, 9, 7, 8, 9, 12, 18, 19, 18, 20, 15, 28, 17, 18, 29, 24, 27, 22, 36, 45, 26, 27, 51, 48, 31, 48, 43, 38, 50, 117, 52, 37, 39, 85, 52, 46, 43, 46, 76, 51, 133, 65, 137, 111, 65, 76, 62, 86, 67, 61, 59, 58, 79, 63, 67, 75, 94, 67, 64, 78, 67, 71, 81, 82, 153, 101, 221 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

MATHEMATICA

NextPrime[n_Integer] := Block[{k}, k = n + 1; While[ !PrimeQ[k], k++ ]; k]; Fortunate[n_Integer] := Block[{p = Product[Prime[i], {i, 1, n}] + 1, q}, q = NextPrime[p]; q - p + 1]; Table[ PrimePi[ Fortunate[n]], {n, 70}] (from Robert G. Wilson v Sep 04 2004)

CROSSREFS

Cf. A005235 A055211 A098166 A098167.

Sequence in context: A113199 A141396 A159849 * A035312 A056230 A119919

Adjacent sequences:  A098165 A098166 A098167 * A098169 A098170 A098171

KEYWORD

nonn

AUTHOR

Pierre CAMI (pierre-cami(AT)bbox.fr), Aug 30 2004

EXTENSIONS

More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 04 2004

Better definition from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 28 2007

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Last modified February 16 19:14 EST 2012. Contains 205945 sequences.