A172126 Members of A181666 of form 3k+1.

1, 4, 10, 16, 40, 64, 85, 160, 256, 340, 640, 682, 1024, 1360, 2560, 2728, 4096, 5440, 5461, 10240, 10912, 16384, 21760, 21844, 40960, 43648, 43690, 65536, 87040, 87376, 163840, 174592, 174760, 262144

Offset

1,2

Comments

Of form 2^m*(4^k-1)/3 and, simultaneously, of form 3l+1, for k>0, l,m>=0.

Links

Table of n, a(n) for n=1..34.

Prog

(PARI) for(n=1, 300000, o=3*n/2^valuation(n, 2)+1; b=ispower(o); if(b&&b%2==0&&round(sqrtn(o, b/2))==4&&(n-1)%3==0, print1(n, ", ")))

Crossrefs

Sequence in context: A009883 A333904 A163389 * A025621 A056486 A233452

Adjacent sequences: A172123 A172124 A172125 * A172127 A172128 A172129

Keyword

nonn

Author

Ralf Stephan, Nov 19 2010

Status

approved