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A249411 Oblong numbers in A249407. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A005369(a(n)) = 1.

LINKS

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

EXAMPLE

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 |        .

PROG

(Haskell)

a249411 n = a249411_list !! (n-1)

a249411_list = filter ((== 1) . a005369) a249407_list

CROSSREFS

Cf. A249407, A005369, subsequence of A002378.

Sequence in context: A240764 A215784 A061780 * A156021 A067348 A002939

Adjacent sequences:  A249408 A249409 A249410 * A249412 A249413 A249414

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Oct 31 2014

STATUS

approved

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Last modified July 15 16:29 EDT 2019. Contains 325049 sequences. (Running on oeis4.)