A124077 Indices of the primes in A072762; b(i=a(n)) is prime, b(i) coded as binary word of length=i with k-th bit set iff k is prime (1<=k<=i).

3, 5, 7, 29, 73, 2131, 4211

Offset: 1

Author

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

Keywords

• hard
• nonn
• more
• base

Comments

A072762(4211) tested as PRP, others certified primes.

A072762(4211) is prime. a(8) > 200000. - Jason Yuen, Oct 26 2024

Examples

			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!
		

Crossrefs

Cf. A072762, A010051.

Programs

Mathematica

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