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 A246755 #27 May 15 2020 02:26:03 %S A246755 15,33,43,45,69,75,87,99,109,135,141,157,159,177,207,213,225,229,249, %T A246755 261,277,283,297,303,307,321,363,375,393,405,423,447,477,499,501,519, %U A246755 531,537,573,591,621,639,643,675,681,691,717,733,739,747,783,789,807,811 %N A246755 Numbers of the form 2k - 1 such that A246702(k) = 3. %C A246755 Composites in this sequence: 15, 33, 45, 69, 75, 87, 99, 135, 141, 159, 177, 207, 213, 225, 249, 261, 297, 303, 321, 363, 375, 393, 405, 423, 447, 477, ... %e A246755 A246702(8) = 3 for the first time, hence a(1) = 2*8 - 1 = 15. %o A246755 (PARI) is(k) = (m=Mod(k%2, k*k)) && sum(i=1, k*k-1, m*=2; m==1) == 3; \\ _Jinyuan Wang_, May 15 2020 %Y A246755 Cf. Numbers of the form 2k - 1 such that A246702(k) = m: number 1 (m = 0), A167791 (m = 1), A246717 (m = 2), this sequence (m = 3), A001133 (primes in this sequence). %K A246755 nonn %O A246755 1,1 %A A246755 _Juri-Stepan Gerasimov_, Nov 15 2014 %E A246755 More terms from and terms corrected by _Jinyuan Wang_, May 15 2020