OFFSET
1,2
COMMENTS
This is the lexicographically earliest sequence of positive numbers with the property that if n is in the sequence, so are n+5 and 3*n.
Suggested by A335365 (which is the complement).
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).
FORMULA
From Colin Barker, Jun 07 2020: (Start)
G.f.: x*(1 + 2*x + 3*x^2 + 2*x^3 - x^6 - x^7 + x^8 - x^10 + x^11 - x^13 + x^14 - x^15 - x^16) / ((1 - x)^2*(1 + x)*(1 + x^2)).
a(n) = a(n-1) + a(n-4) - a(n-5) for n>17.
(End)
PROG
(PARI) Vec(x*(1 + 2*x + 3*x^2 + 2*x^3 - x^6 - x^7 + x^8 - x^10 + x^11 - x^13 + x^14 - x^15 - x^16) / ((1 - x)^2*(1 + x)*(1 + x^2)) + O(x^60)) \\ Colin Barker, Jun 07 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jun 05 2020
STATUS
approved