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 A351336 #32 Nov 24 2024 09:27:51 %S A351336 91,121,671,703,949,1105,1541,1729,1891,2465,2665,2701,2821,3281,3367, %T A351336 3751,4961,5551,6601,7381,8401,8911,10585,11011,12403,14383,15203, %U A351336 15457,15841,16471,16531,18721,19345,23521,24661,24727,28009,29161,29341,30857,31621 %N A351336 Odd pseudoprimes to base 3; composite terms of A271116. %C A351336 Only 2760 of the first 10 million terms of A271116 are nonprimes (0.03%). These composite terms are heavily skewed to rightmost digit = 1. %C A351336 These odd composites all appear in A005935 (A005935 having an additional 27 terms (all parity 0) through the same term = 179146207). %H A351336 Bill McEachen, <a href="/A351336/b351336.txt">Table of n, a(n) for n = 1..5767</a> %F A351336 a(n) ~ (a(n-1)+a(n-2))/2 (conjectured). _Bill McEachen_, Nov 24 2024 %t A351336 q[n_] := CompositeQ[n] && Divisible[Round[3^n/12], n]; Select[Range[32000], q] (* _Amiram Eldar_, Feb 09 2022 *) %o A351336 (PARI) is(n) = (n>1) && !isprime(n) && (lift(Mod(3, 4*n)^(n-1))==1); \\ _Michel Marcus_, Feb 09 2022; after A271116 %o A351336 (PARI) list(lim)=my(v=List()); forcomposite(n=91,lim\1, if(bittest(34,n%6) && Mod(3,n)^(n-1)==1, listput(v,n))); Vec(v) \\ _Charles R Greathouse IV_, Feb 09 2022 %Y A351336 Intersection of A002808 and A271116; intersection of A005935 and A005408; subsequence of A038509. %K A351336 nonn %O A351336 1,1 %A A351336 _Bill McEachen_, Feb 07 2022