A212190 Squares that are the sum of exactly three distinct powers of 2.

25, 49, 81, 100, 196, 289, 324, 400, 529, 784, 1089, 1156, 1296, 1600, 2116, 3136, 4225, 4356, 4624, 5184, 6400, 8464, 12544, 16641, 16900, 17424, 18496, 20736, 25600, 33856, 50176, 66049, 66564, 67600, 69696, 73984, 82944, 102400, 135424, 200704, 263169

Offset: 1

Author

Reinhard Zumkeller, May 03 2012

Keywords

• nonn

Comments

Squares with exactly three ones in their binary representation: A000120(a(n)) = 3;

squares in A014311;

a(n) = A212191(n)^2.

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1000 terms from Reinhard Zumkeller)

Crossrefs

Cf. A010052, A212192.

Programs

Haskell

a212190 n = a212190_list !! (n-1)
a212190_list = filter ((== 1) . a010052) a014311_list

Mathematica

Select[Range[1000]^2, DigitCount[#, 2, 1] == 3&] (* Jean-François Alcover, Nov 07 2016 *)