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 A109578 #6 Jan 04 2019 09:03:41 %S A109578 1,2,0,4,0,4,0,0,0,2,0,4,0,0,0,6,0,6,0,0,0,4,0,0,0,0,0,2,0,14,0,0,0,0, %T A109578 0,6,0,0,0,6,0,10,0,0,0,12,0,0,0,0,0,2,0,0,0,0,0,6,0,2,0,0,0,0,0,14,0, %U A109578 0,0,4,0,8,0,0,0,0,0,4,0,0,0,10,0,0,0,0,0,4,0,0,0,0,0,0,0,6,0,0,0,6,0,6,0,0 %N A109578 a(n) = (pi(n+1)-pi(n)) * (prime(n+1)-prime(n)), where pi(k) is the number of prime numbers less than or equal to k (= A000720(k)) and prime(k) is the k-th prime number (= A000040(k)). %H A109578 Antti Karttunen, <a href="/A109578/b109578.txt">Table of n, a(n) for n = 1..20000</a> %F A109578 a(n) = (A010051(1+n) * A001223(n)). - _Antti Karttunen_, Jan 03 2019 %p A109578 with(numtheory): a:=n->(pi(n+1)-pi(n))*(ithprime(n+1)-ithprime(n)): seq(a(n),n=1..160); %t A109578 an = Table[(PrimePi[n + 1] - PrimePi[n])*(Prime[n + 1] - Prime[n]), {n, 1, 200}] %o A109578 (PARI) A109578(n) = ((primepi(n+1)-primepi(n)) * (prime(n+1)-prime(n))); \\ _Antti Karttunen_, Jan 03 2019 %Y A109578 Cf. A001223, A010051. %Y A109578 Cf. also A096500, A096501. %K A109578 nonn %O A109578 1,2 %A A109578 _Roger L. Bagula_, Jun 29 2005