A351478 Numbers whose sum of even digits is twice the sum of odd digits.

12, 21, 36, 63, 102, 114, 120, 138, 141, 183, 201, 210, 234, 243, 258, 285, 306, 318, 324, 342, 360, 381, 411, 423, 432, 456, 465, 528, 546, 564, 582, 603, 630, 645, 654, 678, 687, 768, 786, 813, 825, 831, 852, 867, 876, 1002, 1014, 1020, 1038, 1041, 1083, 1104, 1116, 1122, 1140, 1161, 1200, 1212

Offset: 1

Author

Eric Angelini and Carole Dubois, Feb 12 2022

Keywords

• base
• nonn

Comments

The sequence is closed under concatenation (if k and m are terms, so are k.m and m.k); permutation of a term's string of digits; and insertion of 0's within a term's string of digits. - Michael S. Branicky, Feb 12 2022

Examples

			a(1) = 12 whose sum of even digits (4) is twice the sum of odd digits (2);
a(2) = 21 whose sum of even digits (4) is twice the sum of odd digits (2);
a(3) = 36 whose sum of even digits (6) is twice the sum of odd digits (3);
etc.
		

Crossrefs

Cf. A036301, A351479.

Programs

Mathematica

Select[Range[1000], Plus @@ Select[IntegerDigits[#], EvenQ] == 2 * Plus @@ Select[IntegerDigits[#], OddQ] &] (* Amiram Eldar, Feb 12 2022 *)

Python

def ok(n):
    ds = list(map(int, str(n)))
    return sum(d for d in ds if d%2==0) == 2*sum(d for d in ds if d%2==1)
print([k for k in range(1, 2173) if ok(k)]) # Michael S. Branicky, Feb 12 2022