1,2

Table of n, a(n) for n=1..9.

Index entries for sequences related to numbers of primes in various ranges

NextPrime[ n_Integer ] := Module[ {k}, k = n + 1; While[ ! PrimeQ[ k ], k++ ]; k ]; c = d = p = q = 0; Do[ While[ d++; d <= 10^n, q = NextPrime[ q ]; p = p + Apply[ Plus, RealDigits[ q ] [[ 1 ] ]]; If[ PrimeQ[ p ], c++ ]]; d--; Print[ c ], {n, 0, 10} ]

Cf. A051351 and A058049.

Sequence in context: A141626 A138292 A138738 * A082651 A241714 A151491

Adjacent sequences: A057570 A057571 A057572 * A057574 A057575 A057576

nonn

Robert G. Wilson v, Nov 27 2000

approved