A078223 a(1) = 2, a(n+1) > a(n) is the smallest multiple of a(n) using only even digits but not divisible by 10 (i.e., having no trailing zeros).

2, 4, 8, 24, 48, 288, 864, 6048, 260064, 26266464, 40082624064, 866826828008064, 26444286042042008448, 20286626620462624006244884224, 22488068646246262608620204848404846444288, 284860000088022466828484860444044822420060828284646488064

Offset: 1

Author

Amarnath Murthy, Nov 23 2002

Keywords

• nonn
• base

Crossrefs

Cf. A078221, A078222, A078224.

Programs

Mathematica

a[n_] := a[n] = Block[{k = 2, b = a[n - 1], c = 2 Range[0, 4]}, While[Mod[k*b,10]==0 || Union@ Join[c, IntegerDigits[k*b]] != c, k++]; k*b]; a[1] = 2; Array[a,14] (* Robert G. Wilson v, May 26 2014 *)

Extensions

More terms from Sascha Kurz, Jan 06 2003

a(14) from Jon E. Schoenfield, Jun 04 2007

a(15) from Chai Wah Wu, Nov 20 2019

a(16) from Chai Wah Wu, Nov 29 2019