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A116537 a(1)=1. a(n) = number of positive integers that are < n, are coprime to n and do not occur among the first n-1 terms of the sequence. 1
1, 0, 1, 1, 3, 1, 4, 2, 3, 2, 6, 3, 7, 4, 4, 5, 9, 3, 10, 4, 7, 5, 13, 4, 12, 7, 11, 6, 16, 4, 17, 8, 10, 9, 12, 6, 21, 9, 14, 8, 23, 6, 24, 11, 13, 13, 27, 9, 25, 10, 19, 12, 30, 9, 22, 13, 21, 15, 33, 9, 34, 15, 21, 17, 27, 12, 39, 17, 28, 13, 41, 14, 42, 19, 24, 20, 36, 15, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,5
LINKS
EXAMPLE
The positive integers which are both less than 9 and are coprime to 9 are 1, 2, 4, 5, 7 and 8. Of these, only the three integers 5, 7 and 8 do not occur earlier in the sequence, so a(9)=3.
PROG
(Perl) #!/usr/bin/perl -w
use Math::PARI qw/ gcd eulerphi /;
$| = 1;
$n = 2;
%seen = (1 => 1);
while (1) {
$v = eulerphi($n) - grep gcd($n, $_) == 1, keys %seen;
$seen{$v} = 1;
++$n;
print "$v ";
} # from Hugo van der Sanden, Mar 30 2006
CROSSREFS
Cf. A096216.
Sequence in context: A135822 A242111 A209919 * A194307 A346770 A048225
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 27 2006
EXTENSIONS
More terms from Hugo van der Sanden, Mar 31 2006
STATUS
approved

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Last modified July 22 00:58 EDT 2024. Contains 374478 sequences. (Running on oeis4.)