A162609 Triangle read by rows in which row n lists n terms, starting with 1, with gaps = n-2 between successive terms.

1, 1, 1, 1, 2, 3, 1, 3, 5, 7, 1, 4, 7, 10, 13, 1, 5, 9, 13, 17, 21, 1, 6, 11, 16, 21, 26, 31, 1, 7, 13, 19, 25, 31, 37, 43, 1, 8, 15, 22, 29, 36, 43, 50, 57, 1, 9, 17, 25, 33, 41, 49, 57, 65, 73, 1, 10, 19, 28, 37, 46, 55, 64, 73, 82, 91, 1, 11, 21, 31, 41, 51, 61, 71, 81

Offset

1,5

Comments

Equals A081493 when first column is removed. - Georg Fischer, Jul 25 2023

Links

Table of n, a(n) for n=1..75.

Formula

T(n,n) = A002061(n-1).

T(n,k) = A076110(n-1,k) = 1+(n-2)*(k-1). - R. J. Mathar, Mar 30 2023

Example

Triangle begins:
  1;
  1,  1;
  1,  2,  3;
  1,  3,  5,  7;
  1,  4,  7, 10, 13;
  1,  5,  9, 13, 17, 21;
  1,  6, 11, 16, 21, 26, 31;

Mathematica

Table[NestList[#+(n-2)&, 1, n-1], {n, 20}]//Flatten (* Harvey P. Dale, Oct 23 2017 *)

Crossrefs

Cf. A002061, A159797, A159798, A162610, A161611, A162612, A162613.

Cf. A060354 (row sums), A081493 (without first column).

Sequence in context: A208814 A230449 A255437 * A194752 A194740 A194762

Adjacent sequences: A162606 A162607 A162608 * A162610 A162611 A162612

Keyword

easy,nonn,tabl

Author

Omar E. Pol, Jul 09 2009

Status

approved