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%I #23 Dec 20 2024 18:16:13
%S 28,57,59,86,115,144,146,175,231,233,289,349,376,407,436,463,494,521,
%T 579,639,666,755,811,987,1101,1103,1217,1275,1451,1565,1567,1681,2029,
%U 2089,2551,2872,2899,3191,3249,3365,4001,4003,4351,4409,4523,4929,5279
%N Numbers k such that 29 is the largest prime factor of k^2 - 1.
%C Numbers k such that A076605(k) = 29.
%C Sequence is finite. For proof see A175607.
%C Search for terms can be restricted to the range from 2 to A175607(10) = 354365441; primepi(29) = 10.
%H Artur Jasinski, <a href="/A181455/b181455.txt">Table of n, a(n) for n = 1..126</a>
%t Select[Range[5600],FactorInteger[#^2-1][[-1,1]]==29&] (* _Harvey P. Dale_, Feb 16 2011 *)
%o (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
%o (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
%Y Cf. A076605, A175607, A181447-A181470, A181568.
%K fini,full,nonn
%O 1,1
%A _Artur Jasinski_, Oct 21 2010