A259527 a(n) gives the number of sequences n = b_1 < b_2 < ... < b_t = A006255(n) such that b_1*b_2*...*b_t is a perfect square.

1, 2, 2, 1, 2, 2, 2, 2, 1, 2, 8, 2, 16, 2, 2, 1, 64, 2, 128, 4, 2, 4, 512, 2, 1, 4, 1, 2, 8192, 2, 8192, 4, 2, 16, 2, 1, 65536, 64, 4, 2, 524288, 8, 1048576, 4, 4, 128, 8388608, 2, 1, 1, 8, 2, 67108864, 4, 2, 2, 4, 256, 536870912, 2, 2147483648, 2048, 2, 1, 1

Offset

1,2

Comments

All terms are powers of 2.

Links

Peter Kagey, Table of n, a(n) for n = 1..1000

Example

For a(20)=4 the solutions are:
s_0 = {20,24,30} with prod(s_0) = 120^2;
s_1 = {20,24,25,30} with prod(s_1) = 600^2;
s_2 = {20,21,24,27,28,30} with prod(s_2) = 15120^2;
s_3 = {20,21,24,25,27,28,30} with prod(s_3) = 75600^2.

Crossrefs

Cf. A006255, A260510.

Sequence in context: A234305 A339701 A304094 * A275992 A271824 A253589

Adjacent sequences: A259524 A259525 A259526 * A259528 A259529 A259530

Keyword

nonn

Author

Peter Kagey, Jun 29 2015

Extensions

More terms from Alois P. Heinz, Jul 16 2015

Status

approved