id:A130200 - OEIS Search Results

Search: id:A130200

Displaying 1-1 of 1 results found.

page 1

Evil triangular numbers.

+0
2

3, 6, 10, 15, 36, 45, 66, 78, 105, 120, 136, 153, 190, 210, 231, 300, 325, 378, 435, 528, 561, 630, 703, 741, 780, 903, 946, 990, 1035, 1128, 1176, 1275, 1326, 1596, 1711, 1830, 1953, 2016, 2080, 2145, 2278, 2415, 2556, 2628, 2701, 2775, 2926, 3081, 3321 (list; graph; listen)

	OFFSET	`1,1`
	FORMULA	`a(n) = A130199(n)/2. Multiplying by 2 doesn't change evilness. Hence evil oblong numbers are twice evil triangular numbers.`
	EXAMPLE	`3 belongs to the sequence because the binary expansion of 3 is 11 - contains an even number of ones.`
	MATHEMATICA	`Select[Table[n(n + 1)/2, {n, 100}], EvenQ[Plus @@ IntegerDigits[ #, 2]] &]`
	CROSSREFS	`Cf. This sequence is the intersection of evil numbers (A001969) and triangular numbers (A000217).` `Sequence in context: A024674 A026104 A058576 this_sequence A151375 A153453 A025215` `Adjacent sequences: A130197 A130198 A130199 this_sequence A130201 A130202 A130203`
	KEYWORD	`nonn`
	AUTHOR	`Tanya Khovanova (tanyakh(AT)yahoo.com), May 16 2007`

page 1

Search completed in 0.002 seconds

Last modified November 27 14:50 EST 2009. Contains 167570 sequences.

AT&T Labs Research