A081427 -id:A081427 - cp's OEIS frontend

A081428 Class 9- primes.

34549, 86371, 103613, 120919, 138059, 149519, 172583, 172741, 224563, 276293, 282059, 282143, 293659, 299417, 316691, 352399, 368513, 379903, 397303, 403061, 414577, 451499, 483179, 486527, 489431, 500947, 506537, 517747, 518047, 541799

Offset: 1

Robert G. Wilson v, Mar 20 2003

nonn

R. K. Guy, Unsolved Problems in Number Theory, A18.

R. J. Mathar, Table of n, a(n) for n = 1..6505

Cf. A005113, A056637, A005109, A005110, A005111, A005112, A081424, A081425, A081426, A081427, A081429, A081430.

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[50000], ClassMinusNbr[ Prime[ # ]] == 9 &]]

A101231 a(n) = n-th prime of Erdős-Selfridge classification n-.

Original entry on oeis.org

2, 29, 67, 179, 941, 4079, 20389, 65267, 224563, 978863, 6448979, 47247763, 309550999, 2150787839, 13925010299

Offset: 1

Jonathan Vos Post, Dec 15 2004

Diagonalization of the Erdős-Selfridge classification of primes.

			a(1) = 2 because 2 is the first element of A005109.
a(2) = 29 because 29 is the 2nd element of A005110.
a(3) = 67 because 67 is the 3rd element of A005111.
a(4) = 179 because 179 is the 4th element of A005112.

R. K. Guy, Unsolved Problems in Number Theory, A18.

Cf. A056637, A005109, A005110, A005111, A005112, A005113, A081424, A081425, A081426, A081427, A081429.

More terms from R. J. Mathar, May 02 2007

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A081428 Class 9- primes.

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A101231 a(n) = n-th prime of Erdős-Selfridge classification n-.

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