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

1,3

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.

Links

Table of n, a(n) for n=1..55.

Example

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.

Sequence in context: A262587 A328724 A039892 * A352290 A350707 A285282

Adjacent sequences: A278642 A278643 A278644 * A278646 A278647 A278648

Keyword

nonn,tabl

Author

Omar E. Pol, Nov 24 2016

Status

approved