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 A100021 #18 Jan 31 2023 14:18:57 %S A100021 0,1,5,7,17,19,29,31,37,53,53,67,77,79,85,97,113,113,127,137,137,151, %T A100021 157,167,187,197,199,209,211,209,247,253,269,265,293,293,305,319,325, %U A100021 337,353,349,377,379,389,383,407,439,449,451,457,473,469,493,505,517,533,533,547 %N A100021 a(n) = 3*prime(n) - prime(n+1) - 3. %C A100021 Except for the initial term, a(n)==(1,5) mod 6. %H A100021 Harvey P. Dale, <a href="/A100021/b100021.txt">Table of n, a(n) for n = 1..1000</a> %F A100021 a(n) = A098764(n) - 3. %p A100021 f:=n->3*ithprime(n)-ithprime(n+1)-3; %t A100021 3#[[1]]-#[[2]]-3&/@Partition[Prime[Range[80]],2,1] (* _Harvey P. Dale_, Oct 13 2018 *) %o A100021 (PARI) a(n) = 3*prime(n) - prime(n+1) - 3; \\ _Michel Marcus_, Jan 31 2023 %Y A100021 Cf. A099389 for the primes arising in the sequence, A098764. %K A100021 nonn,less %O A100021 1,3 %A A100021 _Giovanni Teofilatto_, Nov 20 2004 %E A100021 Corrected by Neven Juric (neven.juric(AT)apis-it.hr), rechecked by _N. J. A. Sloane_, Jun 13 2006