cp's OEIS Frontend

A278817 The least t such that there exists a sequence n = b_1 < b_2 < ... < b_t = A277278(n) such that b_1 + b_2 +...+ b_t is a perfect square.

%I A278817 #12 Dec 01 2016 11:31:54
%S A278817 1,1,3,2,1,5,2,2,6,1,3,3,2,4,3,3,1,2,4,3,3,5,2,2,2,1,3,4,4,2,2,2,3,4,
%T A278817 4,6,1,5,3,2,2,5,5,5,3,3,3,3,2,1,6,6,3,3,3,3,6,6,2,2,2,4,4,3,1,7,7,4,
%U A278817 4,2,2,2,3,3,3,5,5,5,5,4,2,1,2,2,2,5,5
%N A278817 The least t such that there exists a sequence n = b_1 < b_2 < ... < b_t = A277278(n) such that b_1 + b_2 +...+ b_t is a perfect square.
%C A278817 a(n) = 1 if and only if n is square.
%C A278817 a(n) = 2 if and only if A277278(n) = A278818(n).
%H A278817 Peter Kagey, <a href="/A278817/b278817.txt">Table of n, a(n) for n = 0..3000</a>
%e A278817 a(0) = 1 via 0                  = 0^2
%e A278817 a(1) = 1 via 1                  = 1^2
%e A278817 a(2) = 3 via 2 + 3 + 4          = 3^2
%e A278817 a(3) = 2 via 3 + 6              = 3^2
%e A278817 a(4) = 1 via 4                  = 2^2
%e A278817 a(5) = 5 via 5 + 6 + 7 + 8 + 10 = 6^2
%e A278817 a(6) = 2 via 6 + 10             = 4^2
%Y A278817 Cf. A066400, A277278, A278818.
%K A278817 nonn
%O A278817 0,3
%A A278817 _Peter Kagey_, Nov 28 2016