OFFSET
1,2
COMMENTS
The entries at the end of each odd or even block are 1,2,5,14,41,122,363,... and the first differences of these are 1,3,9,27,81,241=powers of 3.
FORMULA
a(n) = round( LambertW(3^((4*n-3)/2)*log(3)/2)/log(3)) = round( LambertW(x*exp((4*n-3)*x))/(2*x) ), where x=log(sqrt(3)). - Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Feb 13 2003
EXAMPLE
a(4)=5, which is odd, so the next terms from a(5) onwards are the next 5 even numbers greater than 5: 6,8,10,12,14. Thus the term 14 is followed by the next 14 odd numbers: 15,17,...,41 and so on.
CROSSREFS
KEYWORD
nonn
AUTHOR
Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 12 2003
STATUS
approved