A164736 Number of n-digit cycles of length 5 under the Kaprekar map A151949.
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 3, 0, 5, 0, 6, 0, 6, 1, 6, 3, 6, 5, 6, 6, 6, 6, 7, 6, 9, 6, 11, 6, 12, 6, 12, 7, 12, 9, 12, 11, 12, 12, 12, 12, 13, 12, 15, 12, 17, 12, 18, 12, 18, 13, 18, 15, 18, 17, 18, 18, 18, 18, 19, 18, 21, 18, 23, 18, 24, 18, 24, 19, 24, 21, 24, 23, 24, 24, 24
Offset: 1
Links
Formula
Conjectures from Chai Wah Wu, Apr 13 2024: (Start)
a(n) = a(n-1) + a(n-2) - 2*a(n-3) + a(n-4) + a(n-5) - 2*a(n-6) + a(n-7) + a(n-8) - a(n-9) for n > 15.
G.f.: x^11*(x^2 + 1)*(x^2 - x + 1)/((x - 1)^2*(x + 1)*(x^6 + x^3 + 1)). (End)