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A048133
Least number which becomes prime or 4 after exactly n iterations of f(x) = sum of prime factors of x.
5
2, 6, 8, 14, 26, 62, 134, 393, 1257, 4659, 9314, 27933, 167073, 334142, 4677862, 14033577, 56134292, 2133102298, 11788191218, 52541651594, 536226160966, 2681130804805, 8512643845707, 129535245187539
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OFFSET
0,1
COMMENTS
f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22.
Identical to the different-offset A121360 except for the second term. - Hans Havermann, Oct 05 2010
a(20) <= 536226160966. a(21) <= 2681130804805. a(22) <= 8512643845707. - Donovan Johnson, Oct 16 2010
a(24) <= 1679460336114602. - Danila Potapov, Dec 01 2024
LINKS
Table of n, a(n) for n=0..23.
CROSSREFS
Cf. A121360 .
Sequence in context: A022112 A107019 A269831 * A199697 A339976 A135619
Adjacent sequences: A048130 A048131 A048132 * A048134 A048135 A048136
KEYWORD
nonn,more
AUTHOR
David W. Wilson
EXTENSIONS
a(17) from Donovan Johnson, Apr 25 2010
a(18)-a(19) from Donovan Johnson, Oct 16 2010
a(20)-a(23) from Danila Potapov, Dec 01 2024
STATUS
approved

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Last modified January 23 23:38 EST 2025. Contains 380173 sequences.
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