cp's OEIS Frontend

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.

A275108 Record gaps between numbers that are either primes or semiprimes.

This page as a plain text file.
%I A275108 #30 Apr 25 2020 08:43:29
%S A275108 1,2,3,4,6,10,11,12,16,18,19,22,24,25,26,30,32,34,36,40,42,44,51,56,
%T A275108 64,66,70,71,78,81,85,86,91,106,110,112,128
%N A275108 Record gaps between numbers that are either primes or semiprimes.
%F A275108 a(n) = A275014(n) - A275013(n).
%e A275108 a(5) = 6 because the next prime or semiprime after 241 is 247, and that is a record gap of size 6.
%o A275108 (PARI) checkrange(a, b, r)=while(b-a>r, forstep(n=a+r, a+1, -1, if(bigomega(n)<3, a=n; next(2))); for(n=a+r+1, b, if(bigomega(n)<3, return([a, n])))); 0
%o A275108 print1(1); p=5; r=1; forprime(q=7, 1e9, if(q-p<=r, p=q; next); t=checkrange(p, q, r); while(t, print1(", "t[2]-t[1]); t=checkrange(t[2], q, r=t[2]-t[1])); p=q) \\ _Charles R Greathouse IV_, Nov 19 2016
%Y A275108 Cf. A037143, A111087, A275013, A275014.
%K A275108 nonn,more
%O A275108 1,2
%A A275108 _Bobby Jacobs_, Nov 13 2016
%E A275108 a(32)-a(37) from _Giovanni Resta_, Apr 25 2020