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 A121763 #19 Dec 23 2024 13:43:30 %S A121763 4,8,9,14,15,19,22,28,29,39,42,43,44,49,53,59,60,64,65,67,74,75,78,80, %T A121763 82,84,85,93,94,98,99,108,109,113,114,117,120,124,127,129,133,140,144, %U A121763 148,152,155,157,158,159,162,163,164,169,183,184,185,194,197,198,199 %N A121763 Numbers n such that 6*n-1 is prime while 6*n+1 is composite. %C A121763 Entries of A024898 which are not in A002822 or equivalently, entries of A046954 which are not in A060461. %H A121763 G. C. Greubel, <a href="/A121763/b121763.txt">Table of n, a(n) for n = 1..10000</a> %t A121763 Select[Range[200], PrimeQ[6# -1] && !PrimeQ[6# +1] &] (* _Ray Chandler_, Aug 22 2006 *) %o A121763 (PARI) for(n=1, 250, if(isprime(6*n-1) && !isprime(6*n+1), print1(n", "))) \\ _G. C. Greubel_, Feb 20 2019 %o A121763 (Magma) [n: n in [1..250] | IsPrime(6*n-1) and not IsPrime(6*n+1)]; // _G. C. Greubel_, Feb 20 2019 %o A121763 (Sage)[n for n in (1..250) if is_prime(6*n-1) and not is_prime(6*n+1)] # _G. C. Greubel_, Feb 20 2019 %o A121763 (GAP) Filtered([1..250], k-> IsPrime(6*k-1) and not IsPrime(6*k+1)); # _G. C. Greubel_, Feb 20 2019 %Y A121763 Cf. A121762, A121765. %K A121763 nonn %O A121763 1,1 %A A121763 _Lekraj Beedassy_, Aug 20 2006 %E A121763 Extended by _Ray Chandler_, Aug 22 2006