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

1,2

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.

Links

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

Example

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

Crossrefs

Cf. A265432, A272671.

See A272685 for another version.

Sequence in context: A004456 A055126 A182336 * A272685 A087979 A291490

Adjacent sequences: A273366 A273367 A273368 * A273370 A273371 A273372

Keyword

sign

Author

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

Status

approved