A366954 The sum of the divisors of the concatenation of 1,2,3,...,n.

1, 28, 168, 1854, 19776, 327152, 1244416, 27319968, 178422816, 22222222056, 2075415810048, 308768621226000, 12455031810211128, 2469135782022242640, 197530862561779410288, 21604938101329359719880, 1821571286217135606177024, 270250398197557076360997936

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Formula

a(n) = sigma(A007908(n)) = A000203(A007908(n)).

Example

a(3)=168 because the divisors of 123 are {1, 3, 41, 123}.

Crossrefs

Cf. A007908, A000203, A110756, A075019, A075022.

Sequence in context: A219298 A197967 A305270 * A129136 A042528 A345215

Adjacent sequences: A366951 A366952 A366953 * A366955 A366956 A366957

Keyword

nonn,base

Author

Sean A. Irvine, Oct 29 2023

Status

approved