A332377 One-third of total number of edges in graph formed by the straight line segments connecting the edges of an equilateral triangle with the n-1 points resulting from a subdivision of the sides into n equal pieces.

1, 4, 13, 18, 41, 48, 85, 94, 145, 156, 221, 234, 313, 328, 415, 438, 545, 564, 685, 700, 841, 864, 1013, 1014, 1201, 1228, 1405, 1434, 1625, 1650, 1861, 1894, 2113, 2148, 2369, 2418, 2665, 2704, 2965, 2988, 3281, 3312, 3613, 3658, 3919, 4008, 4325

Offset

1,2

Links

N. J. A. Sloane, Table of n, a(n) for n = 1..1000

Formula

a(n) = (A092098(n) + A331782(n) - 1)/3 = A332376(n)/3.

Crossrefs

Cf. A091908, A092098 (number of cells), A331782 (number of vertices), A332376.

Sequence in context: A041407 A252976 A065564 * A268720 A191253 A371636

Adjacent sequences: A332374 A332375 A332376 * A332378 A332379 A332380

Keyword

nonn

Author

N. J. A. Sloane, Feb 13 2020

Status

approved