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A292611 Skip 3 triangle numbers, take 1 triangle number, skip 4 triangle numbers, take 2 triangle numbers, skip 5 triangle numbers, take 3 triangle numbers, ... 3
10, 45, 55, 136, 153, 171, 325, 351, 378, 406, 666, 703, 741, 780, 820, 1225, 1275, 1326, 1378, 1431, 1485, 2080, 2145, 2211, 2278, 2346, 2415, 2485, 3321, 3403, 3486, 3570, 3655, 3741, 3828, 3916, 5050, 5151, 5253, 5356, 5460, 5565, 5671, 5778, 5886, 7381 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Sum_{n = (k-1)*k/2+1 .. k*(k+1)/2} a(n) = Sum_{n = (k+1)*(k+2)/2-2 .. (k+2)*(k+3)/2-3} A292610(n) = A222716(k+1) for k > 0.

EXAMPLE

   k|              A292610(n)                 |              a(n)           |       Sum

   ---------------------------------------------------------------------------------------

   0|                                                                           (=    0)

   1|                           1 +   3 +   6 =  10                             (=   10)

   2|                    15 +  21 +  28 +  36 =  45 +  55                       (=  100)

   3|              66 +  78 +  91 + 105 + 120 = 136 + 153 + 171                 (=  460)

   4|       190 + 210 + 231 + 253 + 276 + 300 = 325 + 351 + 378 + 406           (= 1460)

   5| 435 + 465 + 496 + 528 + 561 + 595 + 630 = 666 + 703 + 741 + 780 + 820     (= 3710)

MATHEMATICA

Block[{s = Array[{#, # + 3} &, 11] - 1, 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, A292610.

Sequence in context: A202296 A299530 A238982 * A275623 A245871 A199350

Adjacent sequences:  A292608 A292609 A292610 * A292612 A292613 A292614

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Sep 20 2017

STATUS

approved

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Last modified December 9 08:41 EST 2021. Contains 349627 sequences. (Running on oeis4.)