A278645 Triangle read by rows in which each new term is the sum of its two largest neighbors in the structure.

1, 1, 2, 3, 5, 7, 8, 15, 22, 29, 23, 45, 74, 103, 132, 68, 142, 245, 377, 509, 641, 210, 455, 832, 1341, 1982, 2623, 3264, 665, 1497, 2838, 4820, 7443, 10707, 13971, 17235, 2162, 5000, 9820, 17263, 27970, 41941, 59176, 76411, 93646, 7162, 16982, 34245, 62215, 104156, 163332, 239743, 333389, 427035, 520681

Offset: 1

Author

Omar E. Pol, Nov 24 2016

Keywords

• nonn
• tabl

Comments

To evaluate T(n,k) consider only the two largest neighbors of T(n,k) that are present in the triangle when T(n,k) should be a new term in the triangle.

For the same idea but for a square spiral see A278180; and for a hexagonal spiral see A278619.

It appears that the same idea for an isosceles triangle and also for a square array gives A030237.

Examples

			Triangle begins:
1;
1,    2;
3,    5,     7;
8,    15,    22,    29;
23,   45,    74,    103,   132;
68,   142,   245,   377,   509,    641;
210,  455,   832,   1341,  1982,   2623,   3264;
665,  1497,  2838,  4820,  7443,   10707,  13971,  17235;
2162, 5000,  9820,  17263, 27970,  41941,  59176,  76411,  93646;
7162, 16982, 34245, 62215, 104156, 163332, 239743, 333389, 427035, 520681;
...
		

Crossrefs

Cf. A030237, A278180, A278317, A278619.