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 A014981 #25 Mar 03 2022 11:45:33 %S A014981 1,1,1,1,2,3,7,11,28,120,197,892,2479,4148,11687,56010,271913,461529, %T A014981 2270882,6599404,11263855,56250108,164879269,830987861,7231032935, %U A014981 21386730355,36802336319,109099442316,187943217386 %N A014981 a(n) = c(prime(n))/prime(n), where c = Perrin sequence A001608 (starting 0,2,3,...) and prime(n) is the n-th prime. %H A014981 Seiichi Manyama, <a href="/A014981/b014981.txt">Table of n, a(n) for n = 1..1000</a> (terms 1..200 from T. D. Noe) %H A014981 Ondrej Such, <a href="https://www.jstor.org/stable/2974627">An Insufficient Condition for Primality, Problem 10268</a>, Amer. Math. Monthly, Vol. 103, No. 10 (1996), p. 911. %o A014981 (PARI) c(n) = polsym(x^3-x-1,n)[n+1]; \\ A001608 %o A014981 a(n) = my(p=prime(n)); c(p)/p; \\ _Michel Marcus_, Mar 03 2022 %Y A014981 See A001608, the main entry for the Perrin sequence. %Y A014981 Cf. A000040, A052338, A064723. %K A014981 nonn,easy,nice %O A014981 1,5 %A A014981 _Clark Kimberling_, _Robert G. Wilson v_