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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; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..70.

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}] (* Robert G. Wilson v, Sep 04 2004 *)

CROSSREFS

Cf. A005235 A055211 A098166 A098167.

Sequence in context: A185290 A141396 A159849 * A306441 A207831 A207826

Adjacent sequences:  A098165 A098166 A098167 * A098169 A098170 A098171

KEYWORD

nonn

AUTHOR

Pierre CAMI, Aug 30 2004

EXTENSIONS

More terms from Robert G. Wilson v, Sep 04 2004

Better definition from R. J. Mathar, Oct 28 2007

STATUS

approved

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Last modified November 21 14:56 EST 2019. Contains 329371 sequences. (Running on oeis4.)