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 A154891 #12 Dec 11 2024 12:38:33 %S A154891 1,2,4,9,12,21,24,30,42,45,57,60,75,84,90,105,135,150,165,195,210,255, %T A154891 315,330,390,420,525,630,735,825,840,945,1050,1155,1365,1575,1680, %U A154891 1785,1995,2100,2145,2205,2310,2625,2730,3045,3255,3465,3990,4095,4515,4620 %N A154891 Where records occurs in A154804. %H A154891 Michael S. Branicky, <a href="/A154891/b154891.txt">Table of n, a(n) for n = 1..207</a> %p A154891 A008578 := proc(n) RETURN( n=1 or isprime(n) ) ; end : A154804 := proc(n) local a,d; a := 0 ; for d from 1 to n-1 do if A008578(n-d) and A008578(n+d) then a := a+1; fi; od: a ; end: a804 := [seq(A154804(n),n=1..4000)] ; r := RECORDS(a804)[2] ; # _R. J. Mathar_, Mar 14 2009 %Y A154891 Cf. A008578, A154804, A154720, A154721, A154799. %K A154891 nonn %O A154891 1,2 %A A154891 _Omar E. Pol_, Feb 01 2009 %E A154891 More terms from _R. J. Mathar_, Mar 14 2009 %E A154891 a(50) and beyond from _Michael S. Branicky_, Dec 11 2024