A330579 Numbers k such that the k-th composite number divides the sum of the first k composite numbers.

1, 4, 493, 1565, 6210, 26375, 64019, 289862, 870828, 1244485, 3313113, 4300012, 7946206, 1447234860, 4147639664, 7190149312, 23828369695, 39710847388, 494027033160, 982853084580, 1095174951021, 1141650682059, 1522735118076, 1642938906044

Offset

1,2

Comments

This sequence corresponds to the positions of zeros in A330578.

Links

Table of n, a(n) for n=1..24.

Example

The first 4 composite numbers are: 4, 6, 8 and 9.
As 4 + 6 + 8 + 9 = 3*9, 4 belongs to the sequence.

Prog

(PARI) s=0; k=0; forcomposite (c=4, oo, k++; s+=c; if (s%c==0, print1 (k", ")))

Crossrefs

Cf. A024011 (prime variant), A330578, A330580.

Sequence in context: A053953 A024058 A357536 * A221554 A210310 A324155

Adjacent sequences: A330576 A330577 A330578 * A330580 A330581 A330582

Keyword

nonn,more

Author

Rémy Sigrist, Dec 18 2019

Extensions

a(15)-a(24) from Giovanni Resta, Dec 20 2019

Status

approved