|
|
A022825
|
|
a(n) = a([ n/2 ]) + a([ n/3 ]) + . . . + a([ n/n ]) for n > 1, a(1) = 1.
|
|
15
|
|
|
1, 1, 2, 3, 4, 6, 7, 9, 11, 13, 14, 19, 20, 22, 25, 29, 30, 36, 37, 42, 45, 47, 48, 60, 62, 64, 68, 73, 74, 84, 85, 93, 96, 98, 101, 119, 120, 122, 125, 137, 138, 148, 149, 154, 162, 164, 165, 193, 195, 201, 204, 209, 210, 226, 229, 241, 244, 246, 247, 278, 279
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
FORMULA
|
G.f. A(x) satisfies: A(x) = x + (1/(1 - x)) * Sum_{k>=2} (1 - x^k) * A(x^k). - Ilya Gutkovskiy, Feb 21 2022
|
|
MAPLE
|
a:= proc(n) option remember; `if`(n<2, 1,
add(a(iquo(n, j)), j=2..n))
end:
|
|
MATHEMATICA
|
Fold[Append[#1, Total[#1[[Quotient[#2, Range[2, #2]]]]]] &, {1}, Range[2, 60]] (* Ivan Neretin, Aug 24 2016 *)
|
|
PROG
|
(Python)
from functools import lru_cache
@lru_cache(maxsize=None)
if n <= 1:
return n
c, j = 0, 2
k1 = n//j
while k1 > 1:
j2 = n//k1 + 1
j, k1 = j2, n//j2
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|