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Search: id:A071870
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| A071870 |
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Numbers n such that Lpf(n) > Lpf(n+1) > Lpf(n+2) where Lpf(x) denotes the largest prime factor of x. |
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+0
12
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| 13, 14, 34, 37, 38, 43, 61, 62, 73, 79, 86, 94, 103, 118, 122, 123, 142, 151, 152, 157, 158, 163, 173, 185, 193, 194, 202, 206, 214, 218, 223, 229, 241, 254, 257, 258, 271, 277, 278, 283, 284, 295, 298, 302, 313, 317, 318, 321, 322, 326, 331, 334, 341, 373
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Erdos conjectured that this sequence is infinite.
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REFERENCES
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Erdos P. and Pomerance C., "On the largest prime factors of n and n+1", Aequationes Math. vol. 17, 1978, p. 311-321
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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PROGRAM
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(PARI) for(n=2, 500, if(sign(component(component(factor(n), 1), omega(n))-component(component(factor(n+1), 1), omega(n+1)))+sign(component(component(factor(n+1), 1), omega(n+1))-component(component(factor(n+2), 1), omega(n+2)))==2, print1(n, ", ")))
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CROSSREFS
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Cf. A006530, A070087.
Cf. A071869, A082417-A082422
Sequence in context: A041340 A041338 A042411 this_sequence A041350 A041348 A041346
Adjacent sequences: A071867 A071868 A071869 this_sequence A071871 A071872 A071873
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 09 2002
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