OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = 2*A130202(n). Multiplication by 2 preserves odiousness, hence this sequence is twice odious triangular numbers.
MATHEMATICA
Select[Table[n(n + 1), {n, 100}], OddQ[Plus @@ IntegerDigits[ #, 2]] &]
PROG
(PARI) is(n)=n%2==0 && hammingweight(n)%2 && ispolygonal(n/2, 3) \\ Charles R Greathouse IV, Mar 16 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Tanya Khovanova, May 16 2007
EXTENSIONS
Offset corrected by Amiram Eldar, Dec 09 2019
STATUS
approved