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 A140891 #17 Feb 07 2025 19:38:14
%S A140891 9,49,20,42,41,20,27,33,62,10,39,21,11,39,60,30,49,28,43,41,28,31,49,
%T A140891 55,14,53,53,42,51,29,14,51,22,58,45,22,59,57,55,46,37,29,11,43,60,14,
%U A140891 53,60,42,59,54,27,43,54,26,61,29,15,39,28,31,49,23,58,47,54,27,53,62,42
%N A140891 Binary encoding of the prime-ness of the 6 integers r+14*n with remainder r=1, 3, 5, 9, 11 or 13.
%C A140891 Classify all integers 14n+r with r= 1, 3, 5, 9, 11 or 13 as nonprime or prime and assign hit positions 0=LSB, 1, 2, 3, 4, 5=MSB to the 6 remainders in the same order. Raise the bit if 14n+r is nonprime, erase it if 14n+r is prime.
%C A140891 The sequence interprets this as a number in base 2 and shows the decimal representation.
%e A140891 For n=2, the 6 numbers 29 (r=1), 31 (r=3), 33 (r=5), 37 (r=9), 39 (r=11) and 41 (r=13) are prime, prime, nonprime, prime, nonprime, prime, which is rendered into the binary 001010 = 2^2+2^4=4+16=20=a(2).
%t A140891 f[n_]:=FromDigits[1-Boole[PrimeQ[({13,11,9,5,3,1}+14n)]],2]; Table[f[n],{n,0,100}] (* _Ray Chandler_, Feb 20 2009 *)
%Y A140891 Cf. A105052 (analog in base 10, prime = bit 1, remainder 1 = MSB), A140387 (analog in base 30, prime = bit 0, remainder 1 = LSB).
%K A140891 nonn,base
%O A140891 0,1
%A A140891 _Juri-Stepan Gerasimov_, Jul 07 2008
%E A140891 Corrected and extended by _Ray Chandler_, Feb 20 2009