

A124077


Indices of the primes in A072762; b(i=a(n)) is prime, b(i) coded as binary word of length=i with kth bit set iff k is prime (1<=k<=i).


1




OFFSET

1,1


COMMENTS

A072762(4211) tested as PRP, others certified primes


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

a(3)=7 as A072762(7)=53 and 53 is prime! Also, the binary concatenation of the first a(n) terms of A010051 is prime. E.g. the first 7 term concatenation is binary 0110101 = decimal 53 and is prime!


MATHEMATICA

F[j_] := PrimeQ[Numerator[ Sum[ 1/2^Prime[k], {k, 1, j} ] ]] ; Prime[Select[Range[600], F]]


CROSSREFS

Cf. A072762, A010051.
Sequence in context: A098860 A106920 A060273 * A288891 A322749 A270269
Adjacent sequences: A124074 A124075 A124076 * A124078 A124079 A124080


KEYWORD

hard,nonn


AUTHOR

Anton Vrba (antonvrba(AT)yahoo.com), Nov 24 2006


STATUS

approved



