The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A134231 Triangle T(n, k) = n -k +1 with T(n, n-1) = 2*n-1 and T(n, n) = 1, read by rows. 1
 1, 3, 1, 3, 5, 1, 4, 3, 7, 1, 5, 4, 3, 9, 1, 6, 5, 4, 3, 11, 1, 7, 6, 5, 4, 3, 13, 1, 8, 7, 6, 5, 4, 3, 15, 1, 9, 8, 7, 6, 5, 4, 3, 17, 1, 10, 9, 8, 7, 6, 5, 4, 3, 19, 1, 11, 10, 9, 8, 7, 6, 5, 4, 3, 21, 1, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 23, 1, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 25, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS G. C. Greubel, Rows n = 1..50 of the triangle, flattened FORMULA T(n, k) = A004736(n, k) + A134081(n, k) - I, an infinite lower triangular matrix, where I = Identity matrix. From G. C. Greubel, Feb 17 2021: (Start) T(n, k) = n - k + 1 with T(n, n-1) = 2*n - 1 and T(n, n) = 1. Sum_{k=1..n} T(n, k) = (n-1)*(n+6)/2 + [n=1] = A134227(n). (End) EXAMPLE First few rows of the triangle are: 1; 3, 1; 3, 5, 1; 4, 3, 7, 1; 5, 4, 3, 9, 1; 6, 5, 4, 3, 11, 1; 7, 6, 5, 4, 3, 13, 1; ... MATHEMATICA T[n_, k_]:= If[k==n, 1, If[k==n-1, 2*n-1, n-k+1]]; Table[T[n, k], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Feb 17 2021 *) PROG (Sage) def A134231(n, k): return 1 if k==n else 2*n-1 if k==n-1 else n-k+1 flatten([[A134231(n, k) for k in (1..n)] for n in (1..15)]) # G. C. Greubel, Feb 17 2021 (Magma) A134231:= func< n, k | k eq n select 1 else k eq n-1 select 2*n-1 else n-k+1 >; [A134231(n, k): k in [1..n], n in [1..15]]; // G. C. Greubel, Feb 17 2021 CROSSREFS Cf. A004736, A134081, A134227. Sequence in context: A210952 A208523 A209572 * A225598 A126637 A110091 Adjacent sequences: A134228 A134229 A134230 * A134232 A134233 A134234 KEYWORD nonn,tabl AUTHOR Gary W. Adamson, Oct 14 2007 EXTENSIONS More terms and title changed by G. C. Greubel, Feb 17 2021 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 27 18:55 EDT 2023. Contains 361575 sequences. (Running on oeis4.)