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 A359251 #26 Apr 17 2023 07:50:59 %S A359251 2,3,10,11,14,15,32,33,36,37,60,61,64,65,110,111,114,115,124,125,128, %T A359251 129,176,177,180,181,234,235,238,239,342,343,346,347,356,357,360,361, %U A359251 380,381,384,385,470,471,474,475,578,579,582,583,592,593,596,597,622,623,626,627,792,793,796,797 %N A359251 Sum of terms in an odd-even expansion of n. %C A359251 n stands alone in the first row, and then each row expands to a new row as follows. %C A359251 An even number 2b >= 2 or an odd number 2c+1 >= 3 expands into cells below, below left, and below right, as follows: %C A359251 even odd %C A359251 2b 2c+1 %C A359251 b 0 b c 1 c %C A359251 When expansions overlap, the values add together in the new cells. %C A359251 Any 0 or 1 does not expand and expansions end when a row of only 0's and 1's is reached. %C A359251 This last row is 1,1,1 when n=3 and otherwise always 1,0,1. %C A359251 a(n) is the sum of all cells in all rows, excluding the starting n itself. %e A359251 For n = 4: %e A359251 4 initial row %e A359251 2 0 2 %e A359251 1 0 2 0 1 %e A359251 1 0 1 last row %e A359251 a(4) = (2+2) + (1+2+1) + (1+1). %e A359251 For n = 8: %e A359251 8 %e A359251 4 0 4 %e A359251 2 0 4 0 2 %e A359251 1 0 3 0 3 0 1 %e A359251 1 1 2 1 1 %e A359251 1 0 1 %e A359251 a(8) = (4+4) + (2+4+2) + (1+3+3+1) + (1+1+2+1+1) + (1+1) = 32. %K A359251 nonn,easy %O A359251 2,1 %A A359251 _Moosa Nasir_, Dec 22 2022