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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A171608 Triangle by columns, T(n,k); (..., n, (n+1)) preceded by (n-1) zeros, as an infinite lower triangular matrix. 5
 1, 2, 0, 0, 2, 0, 0, 3, 0, 0, 0, 0, 3, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Let the triangle = M as an infinite lower triangular matrix. M * (1, 2, 3, ...) = A002620: (1, 2, 4, 6, 9, 12, 16, 20, ...); M * (1, 3, 5, ...) = A084265: (1, 2, 6, 9, 15, 20, 28, 35, ...); M * (1, 3, 6, ...) = A028724: (1, 2, 6, 9, 18, 24, 40, 50, ...); Limit_{n->infinity} M^n = A171609: (1, 2, 4, 6, 12, 16, 24, 30, ...). LINKS Micah Manary, Table of n, a(n) for n = 1..5050 FORMULA Triangle by columns, T(n,k); (..., n, (n+1)) preceded by (n-1) zeros, as an infinite lower triangular matrix. EXAMPLE First few rows of the triangle: 1; 2, 0; 0, 2, 0; 0, 3, 0, 0; 0, 0, 3, 0, 0; 0, 0, 4, 0, 0, 0; 0, 0, 0, 4, 0, 0, 0; 0, 0, 0, 5, 0, 0, 0, 0; 0, 0, 0, 0, 5, 0, 0, 0, 0; 0, 0, 0, 0, 6, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0; 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0; ... MAPLE A171609 := proc(n, k) if k = ceil(n/2) then floor( (n+2)/2) ; else 0; end if; end proc: seq(seq( A171609(n, k), k=1..n), n=1..10) ; # R. J. Mathar, Sep 23 2021 CROSSREFS Cf. A002620, A084265, A028724, A171608. Sequence in context: A359240 A280285 A033719 * A307985 A024164 A138805 Adjacent sequences: A171605 A171606 A171607 * A171609 A171610 A171611 KEYWORD nonn,tabl,easy AUTHOR Gary W. Adamson, Dec 12 2009 EXTENSIONS More terms from Micah Manary, Aug 07 2022 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 July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)