cp's OEIS Frontend

A328143 Number of sequences [(b_1, c_1),...,(b_t, c_t)] such that n = b_1 < b_2 < ... < b_t = A328045(n), all c_i are positive integers less than 4, and b_1^c_1*b_2^c_2*...*b_t^c_t is a fourth power.

%I A328143 #11 Oct 07 2019 14:51:42
%S A328143 3,3,2,2,1,12,2,12,12,1,12,192,12,768,12,12,3,12288,12,49152,2,6,48
%N A328143 Number of sequences [(b_1, c_1),...,(b_t, c_t)] such that n = b_1 < b_2 < ... < b_t = A328045(n), all c_i are positive integers less than 4, and b_1^c_1*b_2^c_2*...*b_t^c_t is a fourth power.
%C A328143 When does a(n) = 3*4^A260510(n)? It does for n = 0, 1, 5, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, ...
%C A328143 a(n) = 1 if n is square but not a fourth power.
%C A328143 a(k^4) = 3.
%C A328143 a(24) = 2, a(25) = 1, a(26) = 48, a(27) = 3, and a(28) = 2.
%e A328143 For n = 21 the a(21) = 6 solutions are
%e A328143 21^2 *               27^2 * 28^2 =  126^4,
%e A328143 21^3 * 24^2 *        27^1 * 28^1 =  252^4,
%e A328143 21^2 *        25^2 * 27^2 * 28^2 =  630^4,
%e A328143 21^3 * 24^2 * 25^2 * 27^1 * 28^1 = 1260^4,
%e A328143 21^1 * 24^2 *        27^3 * 28^3 = 1512^4, and
%e A328143 21^1 * 24^2 * 25^2 * 27^3 * 28^3 = 7560^4.
%Y A328143 Cf. A006255, A260510, A277494, A328045.
%Y A328143 A259527 is the analog for squares.
%K A328143 nonn,more
%O A328143 0,1
%A A328143 _Peter Kagey_, Oct 04 2019