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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
EXAMPLE
Distribution of oblong numbers on A249406 and its complement,
m*(m+1) factorizations are shown in respective columns:
. ---+---------+---------+-------- ---+---------+---------+--------
. 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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 31 2014
STATUS
approved

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Last modified February 29 13:31 EST 2024. Contains 370425 sequences. (Running on oeis4.)