A181455 Numbers k such that 29 is the largest prime factor of k^2 - 1.

28, 57, 59, 86, 115, 144, 146, 175, 231, 233, 289, 349, 376, 407, 436, 463, 494, 521, 579, 639, 666, 755, 811, 987, 1101, 1103, 1217, 1275, 1451, 1565, 1567, 1681, 2029, 2089, 2551, 2872, 2899, 3191, 3249, 3365, 4001, 4003, 4351, 4409, 4523, 4929, 5279

Offset: 1

Author

Artur Jasinski, Oct 21 2010

Keywords

• fini
• full
• nonn

Comments

Numbers k such that A076605(k) = 29.

Sequence is finite. For proof see A175607.

Search for terms can be restricted to the range from 2 to A175607(10) = 354365441; primepi(29) = 10.

Links

• Artur Jasinski, Table of n, a(n) for n = 1..126

Crossrefs

Cf. A076605, A175607, A181447-A181470, A181568.

Programs

Magma

[ n: n in [2..6000] | m eq 29 where m is D[#D] where D is PrimeDivisors(n^2-1) ]; // Klaus Brockhaus, Feb 17 2011

Mathematica

Select[Range[5600],FactorInteger[#^2-1][[-1,1]]==29&]  (* Harvey P. Dale, Feb 16 2011 *)

PARI

is(n)=n=n^2-1; forprime(p=2, 23, n/=p^valuation(n, p)); n>1 && 29^valuation(n, 29)==n \\ Charles R Greathouse IV, Jul 01 2013