A264763 a(0) = a(1) = 1; for n>1, a(n) = a(n-1) + (a(n-2) mod 5).

1, 1, 2, 3, 5, 8, 8, 11, 14, 15, 19, 19, 23, 27, 30, 32, 32, 34, 36, 40, 41, 41, 42, 43, 45, 48, 48, 51, 54, 55, 59, 59, 63, 67, 70, 72, 72, 74, 76, 80, 81, 81, 82, 83, 85, 88, 88, 91, 94, 95, 99, 99, 103, 107, 110, 112, 112

Offset: 0

Author

Anders Hellström, Nov 23 2015

Keywords

• nonn
• easy

Crossrefs

Cf. A000045, A003893.

Programs

Magma

[n le 2 select 1 else Self(n-1)+Self(n-2) mod 5: n in [1..60]]; // Vincenzo Librandi, Nov 24 2015

Mathematica

a[0] = a[1] = 1; a[n_] := a[n] = a[n - 1] + Mod[a[n - 2], 5]; Table[a@ n, {n, 0, 60}] (* Michael De Vlieger, Nov 24 2015 *)

PARI

first(m)=my(v=vector(m));v[1]=1;v[2]=1;for(i=3,m,v[i]=v[i-1]+v[i-2]%5);v

Formula

Empirical g.f.: (4*x^12+2*x^11-2*x^10-2*x^9+4*x^8+x^7-2*x^6+x^5+2*x^4+x^3+1) / ((x-1)^2*(x^4+x^3+x^2+x+1)*(x^8-x^6+x^4-x^2+1)). - Colin Barker, Nov 23 2015