A362178 a(1) = 1, a(2) = 2; for n > 2, a(n) is the smallest positive number that has not yet appeared that is a multiple of omega(a(n-1)).
1, 2, 3, 4, 5, 6, 8, 7, 9, 10, 12, 14, 16, 11, 13, 15, 18, 20, 22, 24, 26, 28, 30, 21, 32, 17, 19, 23, 25, 27, 29, 31, 33, 34, 36, 38, 40, 42, 39, 44, 46, 48, 50, 52, 54, 56, 58, 60, 45, 62, 64, 35, 66, 51, 68, 70, 57, 72, 74, 76, 78, 63, 80, 82, 84, 69, 86, 88, 90, 75, 92, 94, 96, 98, 100
Offset: 1
Keywords
Examples
a(5) = 5 as omega(a(4)) = A001221(4) = 1, and 5 is the smallest unused number that is a multiple of 1. a(7) = 8 as omega(a(6)) = A001221(6) = 2, and 8 is the smallest unused number that is a multiple of 2.
Links
- Scott R. Shannon, Image of the first 500000 terms. The green line is a(n) = n.
Programs
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Python
from itertools import count, islice from sympy import primenu def A362178_gen(): # generator of terms a, b = {1,2}, 2 yield from (1,2) while True: for b in count(p:=primenu(b),p): if b not in a: yield b a.add(b) break A362178_list = list(islice(A362178_gen(),20)) # Chai Wah Wu, Apr 12 2023
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