A263549 Numbers k such that k divides the sum of the first k primes with odd indices.

1, 3, 67, 141, 2201, 2625, 8153, 10187, 11089, 136515, 138377, 1543419, 1712109, 5097739, 51562297, 1459124841, 42825210689

Offset

1,2

Comments

a(n) is always an odd number since the first prime is 2.

How do a(n) and A263546(n) compare asymptotically?

Links

Table of n, a(n) for n=1..17.

Example

1 is in the sequence because prime(1) = 2 is divisible by 1.
3 is in the sequence because prime(1) + prime(3) + prime(5) = 2 + 5 + 11 = 18 is divisible by 3.

Mathematica

Select[Range@ 10000, Divisible[Sum[Prime[2 i - 1], {i, 1, #}], #] &] (* Michael De Vlieger, Oct 21 2015 *)

Prog

(PARI) list(lim)=my(v=List(), k, s, t); forprime(p=2, , if((t++) && t%2==1, s+=p; k++; if(s%k==0, listput(v, k)); if(k>=lim, return(Vec(v)))))

Crossrefs

Cf. A045345, A077131, A263541, A263546.

Sequence in context: A142035 A142926 A041983 * A225191 A370659 A201857

Adjacent sequences: A263546 A263547 A263548 * A263550 A263551 A263552

Keyword

nonn,more

Author

Altug Alkan, Oct 21 2015

Extensions

a(17) from Amiram Eldar, Jun 03 2024

Status

approved