A135145 Values of m where A020482(m) != A060308(m-1).

49, 61, 64, 74, 95, 104, 110, 125, 146, 151, 154, 163, 166, 173, 184, 199, 205, 209, 215, 229, 238, 244, 250, 259, 266, 269, 278, 293, 314, 320, 335, 346, 350, 355, 359, 364, 376, 385, 391, 394, 398, 403, 410, 419, 424, 427, 436, 439, 448, 451, 454, 460

Offset

1,1

Comments

Usually the greatest p with p,q both prime, p+q = 2m, is equal to the largest prime <= 2m-2, but not always. These are the exceptions.

Almost all natural numbers are in the sequence so the above comment is misleading in general, and only fitting for small numbers. - Jens Kruse Andersen, Jul 13 2014

Links

Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Mathematica

a2[n_] := {p, q} /. {ToRules @ Reduce[p+q == 2*n, {p, q}, Primes]} // Max; a8[n_] := Max[FactorInteger[(2*n)!/n!^2]]; Select[Range[500], a2[#] != a8[#-1]&] (* Jean-François Alcover, Dec 19 2013 *)

Prog

(PARI) for(m=2, 1000, p=precprime(2*m-2); if(!isprime(2*m-p), print1(m", "))) \\ Jens Kruse Andersen, Jul 12 2014

Crossrefs

Cf. A020482, A060308.

Sequence in context: A304950 A316618 A039472 * A111327 A184033 A178951

Adjacent sequences: A135142 A135143 A135144 * A135146 A135147 A135148

Keyword

nonn

Author

Harry J. Smith, Nov 20 2007

Status

approved