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 A221975 #15 Feb 12 2013 18:26:38
%S A221975 1,3,4,7,10,11,15,22,25,26,31,46,53,56,57,63,94,109,116,119,120,127,
%T A221975 190,221,236,243,246,247,255,382,445,476,491,498,501,502,511,766,893,
%U A221975 956,987,1002,1009,1012,1013,1023,1534,1789,1916,1979,2010,2025,2032,2035,2036
%N A221975 Triangle read by rows of the numbers that are the sum of some consecutive Mersenne numbers A000225.
%F A221975 T(n,k) = sum_{j = n-k+1..n} 2^j - 1, n>=1, k>=1.
%F A221975 T(n,n) = A000295(n+1).
%e A221975 Triangle begins:
%e A221975 1;
%e A221975 3, 4;
%e A221975 7, 10, 11;
%e A221975 15, 22, 25, 26;
%e A221975 31, 46, 53, 56, 57;
%e A221975 63, 94, 109, 116, 119, 120;
%e A221975 127, 190, 221, 236, 243, 246, 247;
%e A221975 255, 382, 445, 476, 491, 498, 501, 502;
%e A221975 ...
%Y A221975 Column 1 is A000225. Right border gives the positive terms of A000295.
%Y A221975 Cf. A023758, A141419, A194939.
%K A221975 nonn,tabl
%O A221975 1,2
%A A221975 _Omar E. Pol_, Feb 12 2013