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 A270795 #5 Apr 06 2016 12:47:52 %S A270795 4,12,21,28,34,42,52,60,65,74,84,95,98,106,119,128,133,135,141,147, %T A270795 170,177,180,192,195,209,214,220,231,246,250,253,284,288,290,295,301, %U A270795 316,323,329,336,339,351,365,382,387,390,394,417,429,432,445,462,470,474,481,490,505,516,518,532,538,543,550,559,566 %N A270795 The prime/nonprime compound sequence BAB. %p A270795 # For Maple code for the prime/nonprime compound sequences (listed in cross-references) see A003622. - _N. J. A. Sloane_, Mar 30 2016 %Y A270795 Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270796, A102216. %K A270795 nonn %O A270795 1,1 %A A270795 _N. J. A. Sloane_, Mar 30 2016