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A048124 Becomes prime or 4 after exactly 2 iterations of f(x) = sum of prime factors of x. +0
1
8, 9, 21, 25, 30, 32, 35, 36, 42, 50, 57, 60, 64, 72, 81, 85, 86, 93, 102, 111, 115, 121, 122, 138, 145, 146, 159, 164, 174, 182, 187, 194, 215, 219, 235, 236, 237, 253, 258, 260, 265, 266, 282, 284, 287, 289, 302, 303, 308, 312, 318, 319, 326, 329, 338, 346 (list; graph; listen)
OFFSET

1,1

COMMENT

f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22.

CROSSREFS

Sequence in context: A120311 A061414 A071869 this_sequence A046258 A074344 A081351

Adjacent sequences: A048121 A048122 A048123 this_sequence A048125 A048126 A048127

KEYWORD

nonn

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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