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 A070748 #12 Apr 24 2022 08:57:52 %S A070748 1,1,-1,1,-1,1,-1,1,-1,-1,-1,-1,-1,-1,1,1,1,-1,-1,1,-1,-1,1,1,1,1,1,1, %T A070748 1,-1,1,-1,-1,1,-1,1,-1,-1,-1,-1,1,-1,1,-1,1,-1,-1,1,1,1,1,1,1,-1,-1, %U A070748 -1,-1,1,1,-1,1,-1,-1,1,-1,1,-1,-1,1,-1,1,1,1 %N A070748 a(n) = signum(sin(prime(n))), where signum=A057427, prime=A000040. %H A070748 Charles R Greathouse IV, <a href="/A070748/b070748.txt">Table of n, a(n) for n = 1..10000</a> %t A070748 Sign[Sin[Prime[Range[10000]]]] (* _Andrey Mitin_, Apr 22 2022 *) %o A070748 (PARI) a(n)=(-1)^(prime(n)/Pi%2\1) \\ _Charles R Greathouse IV_, Jun 13 2013 %Y A070748 Cf. A070747, A070750, A070749, A070753, A070754. %K A070748 sign %O A070748 1,1 %A A070748 _Reinhard Zumkeller_, May 04 2002