OFFSET
1,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..100
MATHEMATICA
PartitionsP /@ Select[Range[1000], AllTrue[FactorInteger[#][[All, 1]], # <= 3 &] &] (* Jean-François Alcover, Oct 13 2021 *)
PROG
(PARI) \\ here is(n) is test for A003586 inclusion.
is(n)={forprime(p=2, 3, n/=p^valuation(n, p)); n==1}
seq(n)={my(A=List(), i=0); while(#A<n, i++; if(is(i), listput(A, numbpart(i)))); Vec(A)} \\ Andrew Howroyd, Jan 02 2020
(Python)
from sympy import integer_log, npartitions
def A117221(n):
def bisection(f, kmin=0, kmax=1):
while f(kmax) > kmax: kmax <<= 1
while kmax-kmin > 1:
kmid = kmax+kmin>>1
if f(kmid) <= kmid:
kmax = kmid
else:
kmin = kmid
return kmax
def f(x): return n+x-sum((x//3**i).bit_length() for i in range(integer_log(x, 3)[0]+1))
return npartitions(bisection(f, n, n)) # Chai Wah Wu, Sep 16 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 04 2006
EXTENSIONS
More terms from Michel Marcus, Apr 20 2019
STATUS
approved