This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A181464 #19 Dec 20 2024 17:41:04
%S A181464 66,68,133,135,202,267,269,334,401,604,671,736,805,937,939,1004,1006,
%T A181464 1205,1272,1274,1341,1473,1475,1540,1609,1676,1741,2078,2143,2145,
%U A181464 2210,2279,2545,2547,2746,2813,2815,2882,2949,3081,3349,3550,3552,3751,3887
%N A181464 Numbers k such that 67 is the largest prime factor of k^2-1.
%C A181464 Numbers k such that A076605(k) = 67.
%C A181464 Sequence is finite, for proof see A175607.
%C A181464 Search for terms can be restricted to the range from 2 to A175607(19) = 25640240468751; primepi(67) = 19.
%H A181464 Artur Jasinski, <a href="/A181464/b181464.txt">Table of n, a(n) for n = 1..976</a>
%t A181464 jj = 2^36*3^23*5^15*7^13*11^10*13^9*17^8*19^8*23^8*29^7*31^7*37^7*41^6 *43^6*47^6*53^6*59^6*61^6*67^6*71^5*73^5*79^5*83^5*89^5*97^5; rr = {}; n = 2; While[n < 14000000, If[GCD[jj, n^2 - 1] == n^2 - 1, k = FactorInteger[n^2 - 1]; kk = Last[k][[1]]; If[kk == 67, AppendTo[rr, n]]]; n++ ]; rr (* _Artur Jasinski_ *)
%t A181464 Select[Range[300000], FactorInteger[#^2-1][[-1, 1]]==67&]
%o A181464 (Magma) [ n: n in [2..300000] | m eq 67 where m is D[#D] where D is PrimeDivisors(n^2-1) ]; // _Klaus Brockhaus_, Feb 19 2011
%o A181464 (PARI) is(n)=n=n^2-1; forprime(p=2, 61, n/=p^valuation(n, p)); n>1 && 67^valuation(n, 67)==n \\ _Charles R Greathouse IV_, Jul 01 2013
%Y A181464 Cf. A076605, A175607, A181447-A181463, A181465-A181470, A181568.
%K A181464 fini,full,nonn
%O A181464 1,1
%A A181464 _Artur Jasinski_, Oct 21 2010