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A076497 Number of primes corresponding to n-th primeval number A072857(n). +0
4
0, 1, 3, 4, 5, 7, 11, 14, 19, 21, 26, 29, 31, 33, 35, 41, 53, 55, 60, 64, 89, 96, 106, 122, 153, 188, 248, 311, 349, 402, 421, 547, 705, 812, 906, 1098, 1162, 1268, 1662 (list; graph; listen)
OFFSET

1,3

LINKS

C. K. Caldwell, The Prime Glossary, Primeval Number

M. Keith, Integers Containing Many Embedded Primes

G. Villemin's Almanach of Numbers, Primeval Records

Wikipedia, Primeval number.

EXAMPLE

The second term in the sequence is 3 because the second primeval number - 13 - can be used to create 3 prime numbers, namely 3, 13 and 31.

MATHEMATICA

Needs["DiscreteMath`Combinatorica`"]; f[n_] := Block[{a = Drop[ Sort[ Subsets[ IntegerDigits[n]]], 1], b = c = {}, k = 1, l}, l = Length[a] + 1; While[k < l, b = Append[b, Permutations[ a[[k]] ]]; k++ ]; b = Union[ Flatten[b, 1]]; l = Length[b] + 1; k = 1; While[k < l, c = Append[c, FromDigits[ b[[k]] ]]; k++ ]; Count[ PrimeQ[ Union[c]], True]]; d = -1; Do[ b = f[n]; If[b > d, Print[b]; d = b], {n, 1, 10^6}]

CROSSREFS

Cf. A072857, A077623, A076730.

Adjacent sequences: A076494 A076495 A076496 this_sequence A076498 A076499 A076500

Sequence in context: A101762 A139455 A095880 this_sequence A046413 A120635 A113533

KEYWORD

more,base,nonn

AUTHOR

Lekraj Beedassy (blekraj(AT)yahoo.com), Nov 08 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 12 2002

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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