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Search: id:A005237
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| A005237 |
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Numbers n such that n and n+1 have same number of divisors.
(Formerly M2068)
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+0
17
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| 2, 14, 21, 26, 33, 34, 38, 44, 57, 75, 85, 86, 93, 94, 98, 104, 116, 118, 122, 133, 135, 141, 142, 145, 147, 158, 171, 177, 189, 201, 202, 205, 213, 214, 217, 218, 230, 231, 242, 243, 244, 253, 285, 296, 298, 301, 302, 326, 332, 334, 344, 374, 375, 381, 387
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 840.
R. K. Guy, Unsolved Problems in Number Theory, B18.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
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FORMULA
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Is a(n) asymptotic to c*n with 9<c<10 ? - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 07 2002
Let S = {(n, a(n): n is a positive integer < 2*10^5}, where a(n) is the above sequence. The best-fit (least squares) line through S has equation y = 9.63976 x - 1453.76. S is very linear: the square of the correlation coefficient of {n} and {a(n)} is about 0.999943. - Joseph L. Pe (joseph_l_pe(AT)hotmail.com), May 15 2003
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CROSSREFS
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Cf. A000005, A005238, A006601, A049051, A006558, A019273, A039665.
Equals A0837951 - 1.
A083795(n-1) - 1.
Sequence in context: A101398 A131221 A138047 this_sequence A140578 A052213 A086263
Adjacent sequences: A005234 A005235 A005236 this_sequence A005238 A005239 A005240
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Jud McCranie (j.mccranie(AT)comcast.net) Oct 15 1997
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