A273369 a(n) is the smallest m such that A265432(m) = A272671(n), or -1 if no such m exists.

1, 15, 14, 13, 12, 217, 0, 215, 45, 213, 44, -1, 43, 209, 42, 207, 2, 573, 1327, 572, 130, -1, 185, 570, 1492, 569, 78, 568, 128, 567, 1318, -1, 1498, 565, 188, 564, 10, 563, 1312, 562, 1504, -1, 1309, 560, 1507, 693, 74, 558, 1510, 557, 192

Offset: 1

Author

Nathan Fox, Brooke Logan, and N. J. A. Sloane, May 20 2016

Keywords

• sign

Comments

Every entry in A265432 appears in A272671.

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.

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

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

Examples

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

Links

• Nathan Fox, Table of n, a(n) for n = 1..62

Crossrefs

Cf. A265432, A272671.

See A272685 for another version.