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 A308268 #24 Jul 15 2024 06:03:37 %S A308268 10,12,15,16,21,25,27,35,39,55,57,65,75,77,85,93,95,115,119,129,143, %T A308268 145,155,183,185,187,189,196,203,205,215,219,231,235,245,253,265,287, %U A308268 295,297,299,305,309,323,325,327,335,341,351,355,357,363,365,375,377,385,395,405,407,413,415,417,429 %N A308268 Numbers k such that 1 + A045763(k) is prime. %C A308268 Numbers k such that k - phi(k) - tau(k) (i.e., k - A000010(k) - A000005(k)) is prime. %C A308268 For distinct primes p and q, p*q is in the sequence if and only if p+q-5 is prime. In particular, 5*p is in the sequence for any prime p. %C A308268 For prime p, 4*p^2 is in the sequence if and only if p is in A308269. %H A308268 Robert Israel, <a href="/A308268/b308268.txt">Table of n, a(n) for n = 1..10000</a> %e A308268 a(3) = 15 is in the sequence because 1 + A045763(15) = 15 - phi(15) - tau(15) = 15 - 8 - 4 = 3 is prime. %p A308268 select(t -> isprime(t - numtheory:-phi(t) - numtheory:-tau(t)), [$1..1000]); %Y A308268 Cf. A000005, A000010, A045763, A308269. %K A308268 nonn %O A308268 1,1 %A A308268 _J. M. Bergot_ and _Robert Israel_, May 17 2019