One possible rule is
Un = (-1493n3 + 13443n2 - 38890n + 36024)/6 for n = 1, 2, 3, 4.
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There are 16 subsets: {0, 5, 7, 12}, {0, 5, 7}, {0, 5, 12}, {0, 7, 12}, {5, 7, 12}, {0, 5}, {0, 7}, {0, 12}, {5, 7}, {5, 12}, {7, 12}, {0], {5}, {7}, {12}, and the empty set.
If a number ends with 0, it is divisible by 10. If a number ends with 5 or 0, it is divisible by 5.
The rule is (-2, -5)
if the number ends on 5 or 0 the number is divisible by 5
If the number ends in 5 or 0 the whole number is divisible by 5.