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 A351332 #21 Mar 27 2022 22:53:58 %S A351332 274177,319489,6700417,825753601,1214251009,6487031809,646730219521, %T A351332 6597069766657,25409026523137,31065037602817,46179488366593, %U A351332 151413703311361,231292694251438081,1529992420282859521,2170072644496392193,3603109844542291969 %N A351332 Primes congruent to 1 (mod 3) that divide some Fermat number. %C A351332 Subsequence of A014752. %D A351332 Allan Cunningham, Haupt-exponents of 2, The Quarterly Journal of Pure and Applied Mathematics, Vol. 37 (1906), pp. 122-145. %H A351332 Wilfrid Keller, <a href="http://www.prothsearch.com/fermat.html">Prime factors k.2^n + 1 of Fermat numbers F_m</a>. %F A351332 A002476 INTERSECT A023394. %e A351332 a(1) = 503^2 + 27*28^2 = 274177 is a prime factor of 2^(2^6) + 1; %e A351332 a(2) = 383^2 + 27*80^2 = 319489 is a prime factor of 2^(2^11) + 1; %e A351332 a(3) = 887^2 + 27*468^2 = 6700417 is a prime factor of 2^(2^5) + 1; %e A351332 a(4) = 27017^2 + 27*1884^2 = 825753601 is a prime factor of 2^(2^16) + 1; %e A351332 a(5) = 2561^2 + 27*6688^2 = 1214251009 is a prime factor of 2^(2^15) + 1; %o A351332 (PARI) isok(p) = if(p%6==1 && isprime(p), my(z=znorder(Mod(2, p))); z>>valuation(z, 2)==1, return(0)); %Y A351332 Cf. A002476, A014752, A023394, A204620, A229850, A229853. %K A351332 nonn %O A351332 1,1 %A A351332 _Arkadiusz Wesolowski_, Feb 07 2022