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

1, 5, 13, 87

Offset: 1

Author

Harvey P. Dale, Aug 30 2025

Keywords

• nonn
• base
• easy
• fini
• full
• new

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

Examples

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

Crossrefs

Cf. A001113, A046975, A098934.

Programs

Mathematica

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

Formula

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