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, 5

Offset: 1

Author

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

Keywords

• nonn
• base
• more

Examples

			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, ...
		

Crossrefs

Cf. A000043, A004426, A074463.

Programs

Mathematica

Floor[Mean[IntegerDigits[#]]]&/@MersennePrimeExponent[Range[47]] (* Harvey P. Dale, Apr 19 2019 *)

Formula

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

Extensions

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

a(48) from Amiram Eldar, Oct 16 2024