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A130199
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Evil oblong (pronic) numbers.
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1
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6, 12, 20, 30, 72, 90, 132, 156, 210, 240, 272, 306, 380, 420, 462, 600, 650, 756, 870, 1056, 1122, 1260, 1406, 1482, 1560, 1806, 1892, 1980, 2070, 2256, 2352, 2550, 2652, 3192, 3422, 3660, 3906, 4032, 4160, 4290, 4556, 4830, 5112, 5256, 5402, 5550, 5852
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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FORMULA
| a(n) = 2*A130200(n). Multiplying by 2 doesn't change evilness. Hence evil oblong numbers are twice evil triangular numbers.
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EXAMPLE
| 6 belongs to the sequence because binary expansion of 6 is 110 - contains an even number of ones.
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MATHEMATICA
| Select[Table[n(n + 1), {n, 100}], EvenQ[Plus @@ IntegerDigits[ #, 2]] &]
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CROSSREFS
| Cf. This sequence is the intersection of evil numbers (A001969) and oblong numbers (A002378).
Sequence in context: A180291 A056930 A064971 * A117343 A028611 A141808
Adjacent sequences: A130196 A130197 A130198 * A130200 A130201 A130202
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KEYWORD
| nonn
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AUTHOR
| Tanya Khovanova (tanyakh(AT)yahoo.com), May 16 2007
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