OFFSET
0,2
COMMENTS
The position numbers for odd numbers 5, 7, 11, 13 and 19 for the first 200 numbers in the sequence are listed in the Comments section of A277215.
EXAMPLE
a(0) = 1 since 0 = 2*(1*2^0 - 1) is the start and end of the first alternating sequence of 1 element and the maximum of its trajectory.
a(5) = 19 since 9232 = 2*(19*3^5 - 1) is the last element in the first alternating sequence of 11 elements - 1214, 607, 1822, 911, 2734, 1367, 4102, 2051, 6154, 3077, 9232 - that ends in the trajectory maximum.
MATHEMATICA
(* we use function altdata[] from A277215 *)
a277875[n_]:=Map[#[[2]]&, altdata[2, n]]
Join[{1, 7}, a277875[99]] (* sequence data *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Hartmut F. W. Hoft, Nov 03 2016
STATUS
approved