A061973 Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 20 (most significant digit on right).

1, 19, 57, 741, 1653, 44707, 1434853, 4392463

Offset

1,2

Comments

This sequence differs from A029537 in that all least significant zeros are kept during concatenation.

No more terms < 8*10^6. - Lars Blomberg, Jul 29 2011

Links

Table of n, a(n) for n=1..8.

Index entries for related sequences

Example

See A061955 for example.

Mathematica

b = 20; c = {}; Select[Range[10^4], Divisible[FromDigits[c = Join[Reverse[IntegerDigits[#, b]], c], b], #] &] (* Robert Price, Mar 09 2020 *)

Prog

(PARI) lista(nn, m=20) = 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: A251073 A176413 A263336 * A041702 A041704 A041706

Adjacent sequences: A061970 A061971 A061972 * A061974 A061975 A061976

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(7)-a(8) from Lars Blomberg, Jul 29 2011

Status

approved