A275247 a(n) = number of decimal digits of A007505(n).

1, 1, 2, 2, 2, 3, 3, 4, 6, 11, 12, 14, 18, 20, 24, 29, 32, 44, 63, 66, 93, 99, 119, 139, 142, 250, 384, 987, 1267, 1546, 2276, 3817, 4486, 5457, 5666, 7734, 7966, 12532, 15470, 21610, 24183, 25795, 26543, 29220, 37217, 46941, 49667, 70671, 124880, 176102, 211335, 219060, 298833, 361552, 370947, 696203, 944108, 1274988, 1833429, 3457035, 3531640, 3580969

Offset

1,3

Links

Table of n, a(n) for n=1..62.

Formula

a(n) = A055642(A007505(n)). - Michel Marcus, Jul 23 2016

Crossrefs

Cf. A055642, A007505 (primes of form 3*2^n-1), A002235 (numbers n such that 3*2^n-1 is prime).

Sequence in context: A341460 A005851 A369786 * A369764 A369987 A293440

Adjacent sequences: A275244 A275245 A275246 * A275248 A275249 A275250

Keyword

base,nonn

Author

Zak Seidov, Jul 21 2016

Status

approved