A292610 Take 3 triangle numbers, skip 1 triangle number, take 4 triangle numbers, skip 2 triangle numbers, take 5 triangle numbers, skip 3 triangle numbers, ...

1, 3, 6, 15, 21, 28, 36, 66, 78, 91, 105, 120, 190, 210, 231, 253, 276, 300, 435, 465, 496, 528, 561, 595, 630, 861, 903, 946, 990, 1035, 1081, 1128, 1176, 1540, 1596, 1653, 1711, 1770, 1830, 1891, 1953, 2016, 2556, 2628, 2701, 2775, 2850, 2926, 3003, 3081, 3160, 3240

Offset

1,2

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Mathematica

Block[{s = Array[{# + 2, #} &, 8], r}, r = PolygonalNumber@ Range@ Total@ Flatten@ s; Map[Function[{a, b}, {First@ #, Set[r, Drop[Last@ #, b]]} &@ TakeDrop[r, a]] @@ # &, s][[All, 1]] // Flatten] (* Michael De Vlieger, Sep 25 2017 *)

Crossrefs

Cf. A000217, A222716, A292611.

Sequence in context: A298015 A256906 A095869 * A069559 A117748 A061066

Adjacent sequences: A292607 A292608 A292609 * A292611 A292612 A292613

Keyword

nonn

Author

Seiichi Manyama, Sep 20 2017

Status

approved