A216416 a(n) = smallest m such that 2n-1 | 10^m+1, or 0 if no such m exists.

1, 0, 0, 3, 0, 1, 3, 0, 8, 9, 0, 11, 0, 0, 14, 0, 0, 0, 0, 0, 0, 0, 0, 23, 21, 0, 0, 0, 0, 29, 30, 0, 0, 0, 0, 0, 4, 0, 3, 0, 0, 0, 0, 0, 22, 3, 0, 0, 48, 0, 2, 17, 0, 0, 54, 0, 56, 0, 0, 0, 11, 0, 0, 21, 0, 65, 9, 0, 4, 23, 0, 3, 0, 0, 74, 0, 0, 0, 39, 0, 33, 0

Offset: 1

Author

V. Raman, Sep 07 2012

Keywords

• nonn

Links

• V. Raman, Table of n, a(n) for n = 1..99.

Crossrefs

Cf. A002326.

Programs

PARI

for(i=0,200,i++;m=0;for(x=1,i,if(((10^x+1))%i==0,m=x;break));print1(m",")) \\ V. Raman, Nov 22 2012