A143310 Triangle read by rows, A000012 * A127446, 1 <= k <= n.

1, 3, 2, 6, 2, 3, 10, 6, 3, 4, 15, 6, 3, 4, 5, 21, 12, 9, 4, 5, 6, 28, 12, 9, 4, 5, 6, 7, 36, 20, 9, 12, 5, 6, 7, 8, 45, 20, 18, 12, 5, 6, 7, 8, 9, 55, 30, 18, 12, 15, 6, 7, 8, 9, 10, 66, 30, 18, 12, 15, 6, 7, 8, 9, 10, 11, 78, 42, 30, 24, 15, 18, 7, 8, 9, 10, 11, 12

Offset

1,2

Comments

Row sums = A143127: (1, 5, 11, 23, 33, 57, 71, ...).

Links

Table of n, a(n) for n=1..78.

Formula

Triangle read by rows, A000012 * A127446, 1 <= k <= n.

Conjecture: T(n,k) = Sum_{i=1..n} [i*k <= n]*i*k. - Mats Granvik, Feb 26 2021

Example

First few rows of the triangle:
   1;
   3,  2;
   6,  2,  3;
  10,  6,  3,  4;
  15,  6,  3,  4,  5;
  21, 12,  9,  4,  5,  6;
  28, 12,  9,  4,  5,  6,  7;
  36, 20,  9, 12,  5,  6,  7,  8;
  ...

Crossrefs

Cf. A127446, A143127.

Sequence in context: A290798 A133519 A135223 * A131897 A061187 A248082

Adjacent sequences: A143307 A143308 A143309 * A143311 A143312 A143313

Keyword

nonn,tabl

Author

Gary W. Adamson, Aug 06 2008

Extensions

Duplicate a(11)-a(15) terms removed by Mats Granvik, Feb 26 2021

Status

approved