A045049 Numbers whose base-4 representation contains exactly two 0's and two 2's.

130, 136, 160, 266, 290, 296, 386, 392, 416, 518, 521, 523, 526, 530, 536, 545, 547, 548, 556, 562, 568, 578, 584, 608, 641, 643, 644, 652, 656, 688, 706, 712, 736, 778, 802, 808, 898, 904, 928, 1050, 1062, 1065, 1067, 1070

Offset

1,1

Links

Enrique Pérez Herrero, Table of n, a(n) for n = 1..100000

Mathematica

fQ[n_] := Block[{idn = IntegerDigits[n, 4]}, Count[idn, 0] == Count[idn, 2] == 2]; Select[Range@1100, fQ] (* Robert G. Wilson v, Dec 11 2017 *)

Prog

(Python)
import numpy as np
for a in range(10000):
    x = np.base_repr(a, base=4)
    if(x.count("0") == 2 and x.count("2") == 2):
        print(a)
# Enrique Pérez Herrero, Dec 06 2017

Crossrefs

Cf. A007090.

Sequence in context: A250740 A025372 A378313 * A163555 A025373 A025364

Adjacent sequences: A045046 A045047 A045048 * A045050 A045051 A045052

Keyword

nonn,base

Author

Clark Kimberling

Status

approved