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 A261406 #5 Aug 22 2015 12:49:42 %S A261406 1,2,3,5,6,7,8,9,10,11,13,16,17,18,20,21,23,24,27,28,29,30,34,37,38, %T A261406 40,42,44,45,47,50,52,56,57,60,63,65,66,70,74,75,76,78,84,86,92,96,98, %U A261406 105,110,118,132,138,144,154,160,165,186,195,204,212,240,270,286,360 %N A261406 Numbers n such that the norm of Phi_n(alpha), the n-th cyclotomic polynomial evaluated at alpha, is +-1, where alpha is the Salem number defined in A073011. %D A261406 Cohen, Henri, Leonard Lewin, and Don Zagier. "A sixteenth-order polylogarithm ladder." Experimental Mathematics 1.1 (1992): 25-34. %Y A261406 Cf. A073011. %K A261406 nonn %O A261406 1,2 %A A261406 _N. J. A. Sloane_, Aug 22 2015