A135076 Primes appearing in A001370.

2, 7, 5, 11, 13, 7, 19, 19, 29, 31, 41, 37, 29, 43, 41, 37, 47, 61, 59, 67, 71, 61, 73, 79, 89, 109, 103, 89, 109, 107, 107, 113, 139, 151, 127, 137, 107, 113, 167, 173, 167, 181, 191, 173, 193, 223, 233, 211, 199, 229, 251, 239, 281, 251, 277, 281, 239, 241, 239, 269

Offset

1,1

Links

Zak Seidov, Table of n, a(n) for n = 1..1000.

Formula

a(n)=A007953(2^A076203(n)).

Example

a(1)=2 because with s=A076203(1)=1, 2^s=2 and sod(2)=2; sod(x)=sum of digits of x;
a(2)=7 because with s=A076203(2)=4, 2^s=16 and sod(16)=7.
a(7)=9 because with s=A076203(7)=12, 2^s=4096 and sod(4096)=19.
a(8)=9 because with s=A076203(8)=18, 2^s=262144 and sod(262144)=19.

Prog

(PARI) lista(nn) = {for (n=1, nn, sd = sumdigits(2^n); if (isprime(sd), print1(sd, ", ")); ); } \\ Michel Marcus, Oct 13 2013

Crossrefs

Cf. A001370, A076203.

Sequence in context: A220606 A232898 A319903 * A155546 A073132 A294075

Adjacent sequences: A135073 A135074 A135075 * A135077 A135078 A135079

Keyword

base,nonn

Author

Zak Seidov, Nov 18 2007

Extensions

Name corrected by Michel Marcus, Oct 13 2013

Status

approved