A155498 Number of odd digits in the concatenation of first n primes.

0, 1, 2, 3, 5, 7, 9, 11, 12, 13, 15, 17, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 33, 34, 36, 38, 40, 42, 44, 47, 49, 52, 55, 58, 60, 63, 66, 68, 70, 73, 76, 78, 81, 84, 87, 90, 92, 93, 94, 95, 97, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 116, 119, 122, 125, 128

Offset

1,3

Comments

Partial sums of A104638. [R. J. Mathar, Feb 13 2009]

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

If n=1, concatenate first 1 prime = 2, then number of odd digits = 0 = a(1).
If n=2, concatenate first 2 primes = 23, then number of odd digits = 1 = a(2).
If n=3, concatenate first 3 primes = 235, then number of odd digits = 2 = a(3).

Maple

ListTools:-PartialSums([seq(nops(select(type, convert(ithprime(i), base, 10), odd)), i=1..100)]); # Robert Israel, Jul 15 2018

Prog

(PARI) a(n) = sum(k=1, n, #select(x->(x%2), digits(prime(k)))); \\ Michel Marcus, Jul 16 2018

Crossrefs

Cf. A000040, A068670.

Sequence in context: A219050 A036049 A092875 * A069149 A042996 A073040

Adjacent sequences: A155495 A155496 A155497 * A155499 A155500 A155501

Keyword

nonn,base

Author

Juri-Stepan Gerasimov, Jan 23 2009

Extensions

Replaced 53 by 55. R. J. Mathar, Feb 13 2009

Status

approved