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 A124929 #18 Sep 08 2022 08:45:28 %S A124929 1,1,3,1,6,7,1,9,21,15,1,12,42,60,31,1,15,70,150,155,63,1,18,105,300, %T A124929 465,378,127,1,21,147,525,1085,1323,889,255,1,24,196,840,2170,3528, %U A124929 3556,2040,511,1,27,252,1260,3906,7938,10668,9180,4599,1023 %N A124929 Triangle read by rows: T(n,k) = (2^k-1)*binomial(n-1,k-1) (1<=k<=n). %C A124929 Row sums give A027649. %H A124929 G. C. Greubel, <a href="/A124929/b124929.txt">Table of n, a(n) for the first 50 rows, flattened</a> %e A124929 First few rows of the triangle are: %e A124929 1; %e A124929 1, 3; %e A124929 1, 6, 7; %e A124929 1, 9, 21, 15; %e A124929 1, 12, 42, 60, 31; %e A124929 1, 15, 70, 150, 155, 63; %e A124929 ... %p A124929 T:=(n,k)->(2^k-1)*binomial(n-1,k-1): for n from 1 to 11 do seq(T(n,k),k=1..n) od; # yields sequence in triangular form %t A124929 Table[(2^k -1)*Binomial[n-1, k-1], {n,12}, {k,n}]//Flatten (* _G. C. Greubel_, Jun 08 2017 *) %o A124929 (PARI) for(n=1,12, for(k=1,n, print1((2^k -1)*binomial(n-1,k-1), ", "))) \\ _G. C. Greubel_, Jun 08 2017 %o A124929 (Magma) [(2^k -1)*Binomial(n-1,k-1): k in [1..n], n in [1..12]]; // _G. C. Greubel_, Nov 19 2019 %o A124929 (Sage) [[(2^k -1)*binomial(n-1,k-1) for k in (1..n)] for n in (1..12)] # _G. C. Greubel_, Nov 19 2019 %o A124929 (GAP) Flat(List([1..12], n-> List([1..n], k-> (2^k -1)*Binomial(n-1,k-1) ))); # _G. C. Greubel_, Nov 19 2019 %Y A124929 Cf. A027649. %K A124929 nonn,tabl %O A124929 1,3 %A A124929 _Gary W. Adamson_, Nov 12 2006 %E A124929 Edited by _N. J. A. Sloane_, Nov 29 2006