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 A151791 #18 Nov 01 2022 09:04:58 %S A151791 1,7,7,42,7,42,42,252,7,42,42,252,42,252,252,1512,7,42,42,252,42,252, %T A151791 252,1512,42,252,252,1512,252,1512,1512,9072,7,42,42,252,42,252,252, %U A151791 1512,42,252,252,1512,252,1512,1512,9072,42,252,252,1512,252,1512,1512,9072,252 %N A151791 a(1)=1; for n > 1, a(n) = 7*6^(wt(n-1)-1). %C A151791 wt(n) is the Hamming weight = binary weight of n (A000120). %H A151791 Michael De Vlieger, <a href="/A151791/b151791.txt">Table of n, a(n) for n = 1..8192</a> %e A151791 From _Omar E. Pol_, Feb 26 2015: (Start) %e A151791 Written as an irregular triangle in which the row lengths are the terms of A011782 the sequence begins: %e A151791 1; %e A151791 7; %e A151791 7,42; %e A151791 7,42,42,252; %e A151791 7,42,42,252,42,252,252,1512; %e A151791 7,42,42,252,42,252,252,1512,42,252,252,1512,252,1512,1512,9072; %e A151791 7,42,42,252,42,252,252,1512,42,252,252,1512,252,1512,1512,9072,42,252,252,1512,252,1512,1512,9072,252,... %e A151791 It appears that the right border gives A003949. %e A151791 It appears that the row sums give A000420. %e A151791 (End) %t A151791 a[n_] := 7*6^(Total@ IntegerDigits[n - 1, 2] - 1); a[1] = 1; Array[a, 57] (* _Michael De Vlieger_, Nov 01 2022 *) %Y A151791 Cf. A011782, A000120, A000420, A151792 (partial sums). %K A151791 nonn,tabf %O A151791 1,2 %A A151791 _N. J. A. Sloane_, Jun 25 2009