login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Table of n, a(n) for n=0..46.

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 * A117343 A286290 A240521

Adjacent sequences:  A130196 A130197 A130198 * A130200 A130201 A130202

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.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 28 14:30 EDT 2017. Contains 288838 sequences.