A351479 - OEIS

A351479

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

123, 132, 147, 174, 213, 231, 312, 321, 345, 354, 369, 396, 417, 435, 453, 471, 534, 543, 567, 576, 639, 657, 675, 693, 714, 741, 756, 765, 789, 798, 879, 897, 936, 963, 978, 987, 1023, 1032, 1047, 1074, 1203, 1227, 1230, 1272, 1302, 1320, 1407, 1470, 1704, 1722, 1740, 2013, 2031, 2103, 2127, 2130, 2172

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OFFSET

1,1

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

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

a(1) = 123 whose sum of odd digits (4) is twice the sum of even digits (2);

a(2) = 132 whose sum of odd digits (4) is twice the sum of even digits (2);

a(3) = 147 whose sum of odd digits (8) is twice the sum of even digits (4).

MATHEMATICA

Select[Range[2000], Plus @@ Select[IntegerDigits[#], OddQ] == 2 * Plus @@ Select[IntegerDigits[#], EvenQ] &] (* Amiram Eldar, Feb 12 2022 *)

PROG

(Python)

def ok(n):

ds = list(map(int, str(n)))