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 A124270 #16 Sep 17 2024 20:42:54 %S A124270 7,19,34,41,53,44,38,103,91,73,99,75,135,142,147,118,133,125,118,193, %T A124270 229,191,212,202,197,201,216,213,248,239,209,248,279,279,277,277,333, %U A124270 325,350,327,299,308,264,309,314,322,297,281,363,374,461,488,484,482 %N A124270 a(n) = prime(A014612(n)) - A014612(prime(n)). Commutator [A000040,A014612] at n. %H A124270 Giovanni Resta, <a href="/A124270/b124270.txt">Table of n, a(n) for n = 1..10000</a> %F A124270 a(n) = A000040(A014612(n)) - A014612(A000040(n)). %F A124270 a(n) = A124268(n) - A124269(n). %e A124270 a(1) = prime(3almostprime(1)) - 3almostprime(prime(1)) = prime(8) - 3almostprime(2) = 19 - 12 = 7. %e A124270 a(2) = prime(3almostprime(2)) - 3almostprime(prime(2)) = prime(12) - 3almostprime(3) = 37 - 18 = 19. %e A124270 a(3) = prime(3almostprime(3)) - 3almostprime(prime(3)) = prime(18) - 3almostprime(5) = 61 - 27 = 34. %o A124270 (PARI) lista(nn) = {p = primes(nn); pp = select(x->bigomega(x)==3, vector(nn, n, n)); for (n=1, nn, print1(p[pp[n]] - pp[p[n]], ", "););} \\ _Michel Marcus_, Oct 15 2014 %Y A124270 Cf. A000040 (primes), A014612 (3-almost primes). %Y A124270 Cf. A124268 (prime(3-almost prime(n))), A124269 (3-almost prime(prime(n))). %Y A124270 Cf. A106349 (prime(semiprime(n))), A106350 (semiprime(prime(n))), A122824 (prime(semiprime(n)) - semiprime(prime(n))). %K A124270 easy,nonn %O A124270 1,1 %A A124270 _Jonathan Vos Post_, Oct 23 2006