A237275 Smallest k divisible by the n-th power of its last decimal digit > 1.

2, 2, 12, 32, 32, 32, 192, 512, 512, 512, 3072, 8192, 8192, 8192, 49152, 131072, 131072, 131072, 786432, 2097152, 2097152, 2097152, 12582912, 33554432, 33554432, 33554432

Offset

0,1

Comments

Conjecture: a(n) == 2 (mod 10).

Links

Table of n, a(n) for n=0..25.

Formula

a(n) = 3*2^n if n mod 4 = 2; 2^(n+2-((n+1) mod 4)) otherwise. - Jon E. Schoenfield, Sep 12 2017

Example

a(0) = 2 because 2 is divisible by 2^0 = 1.
a(1) = 2 because 2 is divisible by 2^1 = 2.
a(2) = 12 because 12 is divisible by 2^2 = 4.

Mathematica

Do[k=1; While[!Total[Transpose[IntegerDigits[k][[-1]]>0&&Mod[k, IntegerDigits[k][[-1]]^n]==0&&!Mod[k, 10]==1], k++]]; Print[n, " ", k-1], {n, 0, 25}]

Crossrefs

Cf. A132359.

Sequence in context: A033886 A185144 A185344 * A087131 A199240 A349529

Adjacent sequences: A237272 A237273 A237274 * A237276 A237277 A237278

Keyword

nonn,base

Author

Michel Lagneau, Apr 22 2014

Status

approved