A212192 Triangular numbers that are the sum of exactly three distinct powers of 2.

21, 28, 276, 1540

Offset

1,1

Comments

Triangular numbers with exactly three ones in their binary representation: A000120(a(n)) = 3; triangular numbers in A014311; no more terms less than A014311(1000000) = 6129982174881536975083663305496791903885182827960991744.

Links

Table of n, a(n) for n=1..4.

Mathematica

Select[Accumulate[Range[60]], Total[IntegerDigits[#, 2]]==3&] (* Harvey P. Dale, Mar 11 2023 *)

Prog

(Haskell)
a212192 n = a212192_list !! (n-1)
a212192_list = filter ((== 1) . a010054) a014311_list

Crossrefs

Cf. A010054, A212190.

Sequence in context: A162692 A048067 A344603 * A166647 A119107 A004196

Adjacent sequences: A212189 A212190 A212191 * A212193 A212194 A212195

Keyword

nonn

Author

Reinhard Zumkeller, May 03 2012

Status

approved