A249411 Oblong numbers in A249407.

2, 12, 30, 42, 72, 110, 156, 210, 272, 342, 380, 420, 462, 552, 650, 756, 870, 992, 1122, 1260, 1406, 1560, 1722, 1892, 2070, 2256, 2450, 2652, 2862, 3080, 3192, 3422, 3660, 3906, 4160, 4422, 4692, 4970, 5256, 5550, 5852, 6162, 6480, 6806, 7140, 7482, 7832

Offset: 1

Author

Reinhard Zumkeller, Oct 31 2014

Keywords

• nonn

Comments

A005369(a(n)) = 1.

Examples

			Distribution of oblong numbers on A249406 and its complement,
m*(m+1) factorizations are shown in respective columns:
.   n | A002378 | A249406 | A249407     n | A002378 | A249406 | A249407
.  ---+---------+---------+--------    ---+---------+---------+--------
.   1 |       2 |         |     1*2    13 |     182 |   13*14 |
.   2 |       6 |     2*3 |            14 |     210 |         |   14*15
.   3 |      12 |         |     3*4    15 |     240 |   15*16 |
.   4 |      20 |     4*5 |            16 |     272 |         |   16*17
.   5 |      30 |         |     5*6    17 |     306 |   17*18 |
.   6 |      42 |         |     6*7    18 |     342 |         |   18*19
.   7 |      56 |     7*8 |            19 |     380 |         |   19*20
.   8 |      72 |         |     8*9    20 |     420 |         |   20*21
.   9 |      90 |    9*10 |            21 |     462 |         |   21*22
.  10 |     110 |         |   10*11    22 |     506 |   22*23 |
.  11 |     132 |   11*12 |            23 |     552 |         |   23*24
.  12 |     156 |         |   12*13    24 |     600 |   24*25 |        .
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..301

Crossrefs

Cf. A249407, A005369, subsequence of A002378.

Programs

Haskell

a249411 n = a249411_list !! (n-1)
a249411_list = filter ((== 1) . a005369) a249407_list