A074464 Average digit (rounded down) in the decimal expansion of a prime number p, where 2^p-1 is a Mersenne prime.

2, 3, 5, 7, 2, 4, 5, 2, 3, 8, 2, 3, 2, 4, 4, 1, 3, 3, 3, 3, 8, 5, 1, 5, 2, 3, 5, 4, 1, 3, 3, 6, 5, 5, 5, 4, 3, 5, 4, 3, 3, 5, 3, 4, 5, 3, 3

Offset

1,1

Links

Table of n, a(n) for n=1..47.

Formula

a(n) = A004426(A000043(n)). - Michel Marcus, Aug 04 2018

Example

Prime numbers for Mersenne are 2,3,5,7,13,17,19,31,61,... so the averages of digits rounded down are 2, 3, 5, 7, (1+3)/2=2, (1+7)/2=4, (1+9)/2=5, (3+1)/2=2, floor((6+1)/2)=3, ...

Mathematica

Floor[Mean[IntegerDigits[#]]]&/@MersennePrimeExponent[Range[47]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 19 2019 *)

Crossrefs

Cf. A000043, A004426, A074463.

Sequence in context: A076779 A337008 A337007 * A074463 A038194 A111309

Adjacent sequences: A074461 A074462 A074463 * A074465 A074466 A074467

Keyword

nonn,base

Author

Y. Kelly Itakura (yitkr(AT)mta.ca), Aug 23 2002

Extensions

a(21)-a(47) from Ivan Panchenko, Aug 03 2018

Status

approved