A228806 Smallest odd number greater than any previous term such that it divides the concatenation of all the previous terms and itself; begin with 1.

1, 5, 15, 25, 29, 35, 125, 625, 2125, 2675, 3125, 15625, 20125, 21875, 23975, 24797, 25125, 36875, 47495, 47725, 51875, 53125, 78125, 135475, 390625, 1171875, 1903875, 1928595, 2142375, 2265625, 6617125, 8385625, 8790525, 8807085, 8818575, 10504785

Offset: 1

Author

Robert G. Wilson v, Sep 04 2013

Keywords

• nonn
• base

Comments

Terms not congruent to 0 (mod 5) are: 1, 29, 24797, 24848081, 91381387, 274144161, ..., .

Terms not congruent to 0 (mod 25) are: 1, 5, 15, 29, 35, 24797, 47495, 1928595, 8807085, 10504785, 24848081, 91381387, 274144161, ..., .

Examples

			a(5) equals 29 because 15152527 (mod 27) == 19, but 15152529 (mod 29) == 0.
		

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..55

Crossrefs

Cf. A171785.

Programs

Mathematica

f[s_List] := Block[{k = s[[-1]] + 2, conc = FromDigits[ Flatten@ IntegerDigits@ s]}, While[ Mod[ conc*10^Floor[ Log[10, k] + 1] + k, k] != 0, k += 2]; Append[s, k]]; Nest[f, {1}, 25]