A074461 Average digit (rounded down) in the decimal expansion of the n-th prime number.

2, 3, 5, 7, 1, 2, 4, 5, 2, 5, 2, 5, 2, 3, 5, 4, 7, 3, 6, 4, 5, 8, 5, 8, 8, 0, 1, 2, 3, 1, 3, 1, 3, 4, 4, 2, 4, 3, 4, 3, 5, 3, 3, 4, 5, 6, 1, 2, 3, 4, 2, 4, 2, 2, 4, 3, 5, 3, 5, 3, 4, 4, 3, 1, 2, 3, 2, 4, 4, 5, 3, 5, 5, 4, 6, 4, 6, 6, 1, 4, 4, 2, 2, 3, 5, 3, 5, 5, 3, 4

Offset: 1

Author

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

Keywords

• easy
• nonn
• base

Examples

			prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, ... so the average digits rounded down are; 2, 3, 5, 7, (1+1)/2 = 1, (1+3)/2 = 2, (1+7)/2 = 4, (1+9)/2 = 5, floor((2+3)/2) = 2, ...
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A004426, A074462.

Programs

PARI

a(n)={my(v=digits(prime(n))); vecsum(v)\#v} \\ Andrew Howroyd, Jan 16 2020

Formula

a(n) = A004426(A000040(n)). - Reinhard Zumkeller, May 27 2010

Extensions

Offset corrected and terms a(21) and beyond from Andrew Howroyd, Jan 16 2020