A387472 Numbers k such that the sum of the first k digits of e is divisible by k.

1, 5, 13, 87

Offset

1,2

Comments

For large n, A046975(n-1)/n is very close to 4.5, so is never an integer. - Alois P. Heinz, Sep 02 2025

Links

Table of n, a(n) for n=1..4.

Formula

{k such that k divides A046975(k-1)}. - Michael S. Branicky, Aug 30 2025

Example

5 is a term since 2+7+1+8+2 = 20 is divisible by 5.

Mathematica

Module[{nn=20000, ed}, ed=RealDigits[E, 10, nn][[1]]; Select[Range[nn], Mod[Total[Take[ed, #]], #]==0&]]

Crossrefs

Cf. A001113, A046975, A098934.

Sequence in context: A359316 A165262 A092955 * A190949 A263468 A350467

Adjacent sequences: A387469 A387470 A387471 * A387473 A387474 A387475

Keyword

nonn,base,easy,fini,full

Author

Harvey P. Dale, Aug 30 2025

Status

approved