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 A293974 Row sums of antidiagonals of the Sierpinski carpet A153490. 3
 1, 2, 2, 4, 5, 4, 6, 6, 4, 8, 10, 8, 13, 14, 10, 14, 13, 8, 14, 16, 12, 18, 18, 12, 16, 14, 8, 16, 20, 16, 26, 28, 20, 28, 26, 16, 29, 34, 26, 40, 41, 28, 38, 34, 20, 34, 38, 28, 41, 40, 26, 34, 29, 16, 30, 36, 28, 44, 46, 32, 44, 40, 24, 42, 48, 36, 54, 54, 36, 48, 42, 24 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also, sums of digits of terms of A292688, or Hamming weights of terms of A292689. See there or A153490 for definition / construction of the Sierpiski carpet. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..19683 FORMULA a(n) = A007953(A292688(n)) = A000120(A292689(n)) = sum(k=1..n, A153490(n,k)), considering A153490 as triangle; could also be indexed as matrix (m,n = 1,...,oo) or "flattened" (linearized) using A000217. MATHEMATICA A293974[i_]:=With[{a=Nest[ArrayFlatten[{{#, #, #}, {#, 0, #}, {#, #, #}}]&, {{1}}, i]}, Array[Total[Diagonal[a, #]]&, 3^i, 1-3^i]]; A293974[5] (* Generates 3^5 terms *) (* Paolo Xausa, May 14 2023 *) PROG (PARI) A293974(n, A=Mat(1))={while(#A

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Last modified December 10 23:37 EST 2023. Contains 367717 sequences. (Running on oeis4.)