A061974 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 21 (most significant digit on right).

1, 5, 25, 125, 155, 160, 421, 1409, 729175, 2804576

Offset

1,2

Comments

This sequence differs from A029538 in that all least significant zeros are kept during concatenation.

No more terms < 7*10^6. - Lars Blomberg, Jul 27 2011

Links

Table of n, a(n) for n=1..10.

Index entries for related sequences

Example

See A061955 for example.

Mathematica

b = 21; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[Reverse[IntegerDigits[#, b]], c], b], #] &] (* Robert Price, Mar 09 2020 *)

Prog

(PARI) lista(nn, m=21) = my(c, t); for(k=1, nn, t+=m^c*fromdigits(Vecrev(digits(k, m)), m); c+=logint(m*k, m); if(t%k==0, print1(k, ", "))); \\ Jinyuan Wang, Dec 05 2020

Crossrefs

Cf. A029447-A029470, A029471-A029494, A029495-A029518, A029519-A029542, A061931-A061954, A061955-A061978.

Sequence in context: A036151 A271380 A036149 * A015950 A337950 A366323

Adjacent sequences: A061971 A061972 A061973 * A061975 A061976 A061977

Keyword

nonn,base,more

Author

Larry Reeves (larryr(AT)acm.org), May 24 2001

Extensions

Edited and updated by Larry Reeves (larryr(AT)acm.org), Apr 12 2002

a(9)-a(10) from Lars Blomberg, Jul 27 2011

Status

approved