A348401 a(n) is the least m > 0 such that n = m! / k! for some k <= m.
1, 2, 3, 4, 5, 3, 7, 8, 9, 10, 11, 4, 13, 14, 15, 16, 17, 18, 19, 5, 21, 22, 23, 4, 25, 26, 27, 28, 29, 6, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 7, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 8, 57, 58, 59, 5, 61, 62, 63, 64, 65, 66, 67, 68, 69
Offset: 1
Keywords
Links
- Rémy Sigrist, PARI program for A348401
Programs
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PARI
See Links section.
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Python
from math import factorial def a(n): f = [factorial(i) for i in range(1, n+1)] for m, fm in enumerate(f, start=1): for fk in f[:m]: if n == fm // fk: return m print([a(n) for n in range(1, 70)]) # Michael S. Branicky, Oct 17 2021
Formula
a(n) <= n.
a(n) < n iff n belongs to A045619 \ {2}.
Comments