A256406 Numbers n such that for some m, A166133(m)=n, A166133(m+1)=n^2-1, in order of increasing m.

3, 198, 270, 570, 522, 600, 822, 882, 1062, 2130, 1950, 2592, 2268, 2310, 3168, 2970, 5502, 6702, 5022, 7350, 10038, 10428, 10500, 9438, 14562, 14010, 15288, 17028, 18060, 19698, 17958, 19890, 18522, 20772, 29670, 20550, 22158, 16650

Offset: 1

Author

N. J. A. Sloane, Apr 01 2015, based on a comment of Franklin T. Adams-Watters in A166133

Keywords

• nonn

Comments

In other words, the next term in A166133 after n is as large as it can be. Terms are listed in order of appearance in A166133.

With the exception of the initial 3, the terms appear to be a (permuted) subset of A014574; i.e. the divisors of a(n)^2-1 are 1, a(n)-1, a(n)+1, and a(n)^2-1. - Hans Havermann, Apr 03 2015

See the "blog" file in A166133 for discussion.

Links

• Hans Havermann and John Mason, Table of n, a(n) for n = 1..6575 [Terms 1 through 480 were computed by Hans Havermann; terms 481 through 6575 by John Mason, Apr 05 2015]

Crossrefs

Cf. A014574, A166133, A256407 (sorted version).

Programs

Haskell

a256406 n = a256406_list !! (n-1)
a256406_list = f a166133_list where
   f (u:vs'@(v:ws)) | u > v || v /= u ^ 2 - 1 = f vs'
                    | otherwise               = u : f ws
-- Reinhard Zumkeller, Apr 01 2015