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 A130199 Evil oblong (pronic) numbers. 1
 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; text; internal format)
 OFFSET 0,1 LINKS FORMULA a(n) = 2*A130200(n). Multiplying by 2 doesn't change evilness. Hence evil oblong numbers are twice evil triangular numbers. EXAMPLE 6 belongs to the sequence because binary expansion of 6 is 110 - contains an even number of ones. MATHEMATICA Select[Table[n(n + 1), {n, 100}], EvenQ[Plus @@ IntegerDigits[ #, 2]] &] CROSSREFS Cf. This sequence is the intersection of evil numbers (A001969) and oblong numbers (A002378). Sequence in context: A180291 A056930 A064971 * A295904 A117343 A286290 Adjacent sequences:  A130196 A130197 A130198 * A130200 A130201 A130202 KEYWORD nonn AUTHOR Tanya Khovanova, May 16 2007 STATUS approved

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Last modified November 17 23:16 EST 2018. Contains 317279 sequences. (Running on oeis4.)