This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A130202 Odious triangular numbers. 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 FORMULA a(n) = A130201(n)/2. Multiplication by 2 preserves odiousness, hence this sequence is odious oblong numbers divided by 2. MATHEMATICA Select[Table[n(n + 1)/2, {n, 100}], OddQ[Plus @@ IntegerDigits[ #, 2]] &] Select[Accumulate[Range[100]], OddQ[DigitCount[#, 2, 1]]&] (* Harvey P. Dale, Dec 04 2016 *) CROSSREFS Cf. This sequence is the intersection of odious (A000069) and triangular (A000217) numbers. Sequence in context: A048012 A254368 A276674 * A162692 A048067 A212192 Adjacent sequences:  A130199 A130200 A130201 * A130203 A130204 A130205 KEYWORD nonn AUTHOR Tanya Khovanova, May 16 2007 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

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