A235500 Numbers k such that k and all its prefixes are a multiple of the difference between their length and their last digit.

0, 2, 20, 21, 23, 24, 202, 204, 210, 212, 214, 216, 232, 234, 240, 242, 244, 246, 2020, 2022, 2023, 2025, 2026, 2028, 2040, 2042, 2043, 2045, 2046, 2048, 2100, 2102, 2103, 2105, 2106, 2108, 2120, 2121, 2122, 2123, 2125, 2126, 2127, 2128, 2140, 2142, 2143

Offset

1,2

Comments

The sequence has 1117896 terms, all beginning with 2, apart 0. The largest term is 2160088425040528890600488466.

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000

Example

2128 is a term because 2 is divisible by (1-2), 21 by (2-1), 212 by (3-1) and 2128 by (4-8).

Mathematica

r[v_, nd_] := Block[{w=10*v, d=nd+1}, Do[ If[w < 10^4 && i != d && Mod[w, d-i] == 0, Sow@ w; r[w, d]]; w++, {i, 0, 9}]]; Union[{0, 2}, Reap[r[2, 1]][[2, 1]]] (* terms < 10^4 *)

Crossrefs

Cf. A144688.

Sequence in context: A217394 A072998 A024629 * A319953 A111193 A136906

Adjacent sequences: A235497 A235498 A235499 * A235501 A235502 A235503

Keyword

nonn,base,fini

Author

Giovanni Resta, Jan 11 2014

Status

approved