A259615 a(0)=0, a(1)=a(2)=a(3)=a(4)=1; thereafter, a(n) = Sum_{k=1..5} a(n-k-(a(n-k) mod 5)).

0, 1, 1, 1, 1, 3, 4, 5, 9, 9, 11, 19, 23, 27, 45, 87, 105, 205, 401, 587, 747, 1121, 1763, 2145, 4085, 7965, 15529, 16545, 32503, 38323, 49767, 74305, 146847, 180069, 210427, 341745, 650987, 787109, 917411

Offset: 0

Author

Anders Hellström, Jun 30 2015

Keywords

• nonn

Links

• Robert G. Wilson v, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000322, A241154 (sequence obtained without mod 5 in formula).

Programs

Ruby

def first(m)
    v=[0,1,1,1,1]
    for i in 5..m-1
      i2=0
      for j in 1..5
        r=i-j
        i2 += v[r-v[r]%5]
      end
      v << i2
    end
    v
end

Sage

def first(m):
    v=[0,1,1,1,1]
    for i in range(5,m+1):
      l=0
      for s in range(1,5+1):
        l += v[i-s-v[i-s]%5]
      v.append(l)
    return v