A093482 a(n) = the least positive k such that (n+k)+1 and (n*k)+1 are both squares; or 0 if no such k exists.

0, 0, 5, 20, 3, 0, 0, 55, 215, 0, 13, 0, 11, 0, 209, 1139, 0, 0, 80, 4, 3, 0, 25, 551, 23, 0, 0, 1196, 0, 0, 8993, 0, 0, 0, 1189, 84, 0, 0, 41, 0, 39, 0, 0, 180, 1323, 0, 0, 2255, 30575, 0, 0, 0, 1315, 0, 8, 168, 0, 0, 61, 380, 59, 0, 80, 67535, 1615, 0, 0, 156, 371, 0

Offset

1,3

Comments

For n >1 if a(n) = m then a(m) = n. Subsidiary sequence: indices of zero.

Links

Table of n, a(n) for n=1..70.

Example

a(3) = 5, 3+5 +1 =9 and 3*5 +1 = 16 are both Squares.

Crossrefs

Cf. A093481.

Sequence in context: A104314 A302662 A261545 * A283522 A199363 A199588

Adjacent sequences: A093479 A093480 A093481 * A093483 A093484 A093485

Keyword

nonn

Author

Amarnath Murthy, Apr 14 2004

Extensions

More terms from Don Reble, Oct 26 2006

Status

approved