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Search: id:A130202
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| A130202 |
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Odious triangular numbers. |
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+0
2
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| 1, 21, 28, 55, 91, 171, 253, 276, 351, 406, 465, 496, 595, 666, 820, 861, 1081, 1225, 1378, 1431, 1485, 1540, 1653, 1770, 1891, 2211, 2346, 2485, 2850, 3003, 3160, 3240, 3403, 3655, 3916, 4186, 4371, 4560, 4753, 4950
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OFFSET
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0,2
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FORMULA
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a(n) = A130201(n)/2. Multiplication by 2 preserves odiousness, hence this sequence is odious oblong numbers divided by 2.
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MATHEMATICA
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Select[Table[n(n + 1)/2, {n, 100}], OddQ[Plus @@ IntegerDigits[ #, 2]] &]
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CROSSREFS
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Cf. This sequence is the intersection of odious (A000069) and triangular (A000217) numbers.
Sequence in context: A120735 A009727 A048012 this_sequence A162692 A048067 A166647
Adjacent sequences: A130199 A130200 A130201 this_sequence A130203 A130204 A130205
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KEYWORD
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nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), May 16 2007
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