

A162609


Triangle read by rows in which row n lists n terms, starting with 1, with gaps = n2 between successive terms.


9



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
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OFFSET

1,5


COMMENTS

Note that the last term of the nth row is the central polygonal number A002061(n1).


LINKS

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


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[#+(n2)&, 1, n1], {n, 20}]//Flatten (* Harvey P. Dale, Oct 23 2017 *)


CROSSREFS

Cf. A002061, A159797, A159798, A162610, A161611, A162612, A162613.
Cf. A060354 (row sums).  R. J. Mathar, Jul 20 2009
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



