A273369 - OEIS

%I #14 Aug 01 2021 01:56:17

%S 1,15,14,13,12,217,0,215,45,213,44,-1,43,209,42,207,2,573,1327,572,

%T 130,-1,185,570,1492,569,78,568,128,567,1318,-1,1498,565,188,564,10,

%U 563,1312,562,1504,-1,1309,560,1507,693,74,558,1510,557,192

%N a(n) is the smallest m such that A265432(m) = A272671(n), or -1 if no such m exists.

%C Every entry in A265432 appears in A272671.

%C a(n) = -1 whenever A272671(n) ends in 0, because every such entry ends in 00 and anytime concat(1,k,00) and concat(n,k,00) are both perfect squares, concat(1,k) and concat(n,k) are also both perfect squares.

%C Does every term in A272671 that does not end in 0 appear in A265432?

%C See A272685 for a version that takes into account the fact that terms in A272671 ending in 0 cannot appear in A265432.

%H Nathan Fox, <a href="/A273369/b273369.txt">Table of n, a(n) for n = 1..62</a>

%e A272671(6) = 156. A265432(217) = 156, but A265432(m) does not equal 156 for any m < 217. So a(6) = 217.

%Y Cf. A265432, A272671.

%Y See A272685 for another version.

%K sign

%O 1,2

%A _Nathan Fox_, _Brooke Logan_, and _N. J. A. Sloane_, May 20 2016