A365199 a(n) is the index of the n-th occurrence of 1 in A365203.

1, 14, 53, 109, 221, 445, 893, 1789, 3581, 7165, 14333, 28669, 84530, 295033, 830369, 1660741, 4755764, 10372048, 28287409, 56574821, 153253317, 323636916, 848150626, 2217511139, 6534867338, 20173498129, 40346996261, 120496984345

Offset

1,2

Links

Chai Wah Wu, Table of n, a(n) for n = 1..31

Example

a(1) =   1 since A365203(1)   = 1 (1st occurrence of 1).
a(2) =  14 since A365203(14)  = 1 (2nd occurrence of 1).
a(3) =  53 since A365203(53)  = 1 (3rd occurrence of 1).
a(4) = 109 since A365203(109) = 1 (4th occurrence of 1).

Maple

A365203 := proc(n) option remember; if n = 1 then 1; elif procname(n - 1) < n then procname(n - 1) + n; elif n = procname(n - 1) then n*n; elif irem(procname(n - 1), n) = 0 then procname(n - 1)/n; else procname(n - 1) - n; end if; end proc;
A365199 := proc(n) if A365203(n) = 1 then n; end if; end proc;
seq(A365199(n), n = 1 .. 200000000);

Prog

(Python)
from itertools import count, islice
def A365199_gen(): # generator of terms
    yield (a:=1)
    for n in count(2):
        if a<n:
            a += n
        elif a==n:
            a = n**2
        elif a%n:
            a -= n
        else:
            a //= n
        if a == 1:
            yield n
A365199_list = list(islice(A365199_gen(), 10)) # Chai Wah Wu, Sep 23 2023

Crossrefs

Cf. A365203.

Sequence in context: A332594 A338165 A217077 * A214659 A241354 A240811

Adjacent sequences: A365196 A365197 A365198 * A365200 A365201 A365202

Keyword

nonn,hard

Author

Felix Huber, Aug 26 2023

Extensions

a(22)-a(23) from Michel Marcus, Aug 28 2023

a(24)-a(28) from Chai Wah Wu, Sep 23 2023

Status

approved