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A118176 a(1) = 1. a(n) = number of earlier terms of the sequence which have a different number of divisors than n. 2
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; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A118177(n) is the number of divisors of a(n).

LINKS

M. F. Hasler, Nov 06 2006, Table of n, a(n) for n = 1..100

EXAMPLE

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.

MAPLE

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, Nov 06 2006

CROSSREFS

Cf. A118177.

Sequence in context: A096776 A280687 A271774 * A005731 A132962 A046145

Adjacent sequences:  A118173 A118174 A118175 * A118177 A118178 A118179

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 13 2006

EXTENSIONS

More terms from M. F. Hasler, Nov 06 2006

STATUS

approved

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Last modified September 20 12:42 EDT 2017. Contains 292271 sequences.