OFFSET
1,4
COMMENTS
LINKS
Index entries for linear recurrences with constant coefficients, signature (2, -3, 4, -5, 6, -5, 4, -3, 2, -1).
FORMULA
a(6*k) = 5, a(6*k+1) = 6, a(6*k+2) = a(6*k+3) = 6*k, a(6*k+4) = 6*k+3, a(6*k+5) = 6*k+4 for k > 1.
Conjectures from Colin Barker, May 14 2018: (Start)
G.f.: x*(1 - x + 2*x^2 + 2*x^3 + 2*x^5 - x^6 + 4*x^7 - 3*x^8 + x^9 - x^10 - 2*x^11 + 2*x^12 - x^13 + x^14 + x^15 - x^16) / ((1 - x)^2*(1 - x + x^2)^2*(1 + x + x^2)^2).
a(n) = 2*a(n-1) - 3*a(n-2) + 4*a(n-3) - 5*a(n-4) + 6*a(n-5) - 5*a(n-6) + 4*a(n-7) - 3*a(n-8) + 2*a(n-9) - a(n-10) for n>17.
(End)
PROG
(PARI) q=vector(85); q[1]=1; q[2]=1; q[3]=1; q[4]=5; q[5]=6; q[6]=4; for(n=7, #q, q[n] = q[n-q[n-2]]+q[n-q[n-4]]); q
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Altug Alkan, May 13 2018
STATUS
approved