###How?
Ɠ⁽¿ÇB31_+2¦4ḍ~ƊR;€"J$ḅ³Fċ:³$ - Main Link
Ɠ - set the chain's left argument, N, to evaluated STDIN
⁽¿Ç - base 250 integer = 3765
B - to binary = [1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1]
31_ - 31 minus = [30,30,30,31,30,31,30,30,31,30,31,30]
Ɗ - last three links as a monad - f(N):
4ḍ - four divides (N)?
~ - bitwise NOT (0 becomes -1 and 1 becomes -2)
¦ - sparse application...
2 - ...to indices: [2]
+ - ...action: add
i.e. x=9 or 8: [30,2x,30,31,30,31,30,30,31,30,31,30]
R - range (vectorises) = [[1,2,...30],...]
$ - last two links as a monad - f(that):
J - range of length = [1,2,...,12]
" - zip with:
;€ - concatenate each -> [[[1,1],[2,1],...,[30,1]],...]
ḅ - convert from base (vectroises):
³ - 100 -> [[101,201,...,3001],...]
F - flatten
ċ - count occurrences of:
$ - last two links as a monad - f(N):
: - (N) integer divide:
³ - 100
