A045015 Numbers whose base-4 representation contains no 0's and exactly two 1's.

5, 22, 23, 25, 29, 37, 53, 90, 91, 94, 95, 102, 103, 105, 109, 118, 119, 121, 125, 150, 151, 153, 157, 165, 181, 214, 215, 217, 221, 229, 245, 362, 363, 366, 367, 378, 379, 382, 383, 410, 411, 414, 415, 422, 423, 425, 429, 438

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..3000

Mathematica

Select[Range[10000], DigitCount[#, 4, 0] == 0 && DigitCount[#, 4, 1] == 2 &] (* Vincenzo Librandi, Sep 21 2016 *)

Prog

(Python)
from sympy.ntheory import count_digits
def ok(n): c = count_digits(n, 4); return 0 not in c and c[1] == 2
print(list(filter(ok, range(439)))) # Michael S. Branicky, May 22 2021

Crossrefs

Cf. A007090.

Sequence in context: A217444 A063619 A229801 * A283758 A288676 A085101

Adjacent sequences: A045012 A045013 A045014 * A045016 A045017 A045018

Keyword

nonn,base

Author

Clark Kimberling

Status

approved