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 A104569 Triangle read by rows: T(i,j) is the (i,j)-entry (1 <= j <= i) of the product Q*R of the infinite lower triangular matrices Q = [1; 1,3; 1,3,1; 1 3,1,3; ...] and R = [1; 1,1; 1,1,1; 1,1,1,1; ...]. 2
 1, 4, 3, 5, 4, 1, 8, 7, 4, 3, 9, 8, 5, 4, 1, 12, 11, 8, 7, 4, 3, 13, 12, 9, 8, 5, 4, 1, 16, 15, 12, 11, 8, 7, 4, 3, 17, 16, 13, 12, 9, 8, 5, 4, 1, 20, 19, 16, 15, 12, 11, 8, 7, 4, 3, 21, 20, 17, 16, 13, 12, 9, 8, 5, 4, 1, 24, 23, 20, 19, 16, 15, 12, 11, 8, 7, 4, 3, 25, 24, 21, 20, 17, 16, 13 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA For 1<=j<=i: T(i, j)=2(i-j+1) if i and j are of opposite parity; T(i, j)=2(i-j)+1 if both i and j are odd; T(i, j)=2(i-j)+3 if both i and j are even. - Emeric Deutsch, Mar 23 2005 EXAMPLE The first few rows of the triangle are:   1;   4, 3;   5, 4, 1;   8, 7, 4, 3;   9, 8, 5, 4, 1;   ... MAPLE T:=proc(i, j) if j>i then 0 elif i+j mod 2 = 1 then 2*(i-j)+2 elif i mod 2 = 1 and j mod 2 = 1 then 2*(i-j)+1 elif i mod 2 = 0 and j mod 2 = 0 then 2*(i-j)+3 else fi end: for i from 1 to 13 do seq(T(i, j), j=1..i) od; # yields sequence in triangular form # Emeric Deutsch, Mar 23 2005 CROSSREFS Cf. A035608, A074377, A104570. Row sums yield A074377. Columns 1, 3, 5, ... (starting at the diagonal entry) yield A042948. Columns 2, 4, 6, ... (starting at the diagonal entry) yield A014601. The product R*Q yields A104570. Sequence in context: A075128 A074091 A177033 * A093619 A134186 A024688 Adjacent sequences:  A104566 A104567 A104568 * A104570 A104571 A104572 KEYWORD nonn,tabl AUTHOR Gary W. Adamson, Mar 16 2005 EXTENSIONS More terms from Emeric Deutsch, Mar 23 2005 STATUS approved

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Last modified April 7 04:08 EDT 2020. Contains 333292 sequences. (Running on oeis4.)