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Search: id:A118176
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| A118176 |
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a(1) = 1. a(n) = number of earlier terms of the sequence which have a different number of divisors than n. |
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+0
2
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| 1, 1, 2, 3, 2, 5, 2, 7, 8, 8, 4, 11, 5, 11, 12, 15, 7, 16, 8, 18, 16, 17, 11, 23, 23, 21, 21, 25, 14, 29, 15, 29, 24, 25, 26, 35, 20, 27, 27, 38, 24, 39, 26, 40, 41, 30, 29, 47, 45, 45, 35, 46, 33, 49, 36, 51, 37, 38, 38, 59, 39, 39, 57, 63, 40, 60, 45, 60, 44, 64, 49, 69, 51, 47
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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A118177(n) is the number of divisors of a(n).
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LINKS
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M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 06 2006, Table of n, a(n) for n = 1..100
Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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11 has 2 divisors. So a(11) = the number of terms among the first 10 terms of the sequence which do not have 2 divisors. Only the four terms a(1) = 1, a(2) = 1, a(9) = 8 and a(10) = 8 each do not have 2 divisors. So a(11) = 4.
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MAPLE
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a:=proc(n)option remember; if n=1 then 1 else nops( subs( numtheory[tau](n)=NULL, [ 'numtheory[tau](a(i))', $i=1..n-1 ] )) fi end; - M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 06 2006
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CROSSREFS
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Cf. A118177.
Sequence in context: A094757 A095171 A096776 this_sequence A005731 A132962 A046145
Adjacent sequences: A118173 A118174 A118175 this_sequence A118177 A118178 A118179
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Apr 13 2006
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EXTENSIONS
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More terms from M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Nov 06 2006
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