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

1,1

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]

Prog

(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

Crossrefs

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

Sequence in context: A209120 A336250 A256407 * A157565 A157598 A023310

Adjacent sequences: A256403 A256404 A256405 * A256407 A256408 A256409

Keyword

nonn

Author

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

Status

approved