id:A127370 - OEIS Search Results

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a(1)=1. a(n) = number of positive integers <= n and coprime to (sum{k=1 to n-1} a(k)).

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1, 2, 2, 4, 4, 6, 7, 4, 2, 5, 11, 4, 6, 7, 11, 8, 5, 18, 19, 6, 6, 7, 19, 12, 12, 13, 18, 19, 12, 12, 16, 16, 10, 16, 14, 18, 17, 26, 32, 35, 11, 39, 22, 15, 30, 31, 19, 45, 25, 34, 51, 22, 24, 22, 19, 52, 53, 29, 32, 57, 31, 34, 59, 17, 45, 26, 34, 26, 35, 47, 36, 30, 37, 45, 21 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Leroy Quet, Home Page (listed in lieu of email address)`
	EXAMPLE	`The sum of the first 8 terms of the sequence is 30. So a(9) is the number of positive integers <= 9 and coprime to 30. There are two such integers, 1 and 7. So a(9) = 2.`
	MAPLE	`a[1]:=1: for n from 2 to 100 do ct:=0: for j from 1 to n do if gcd(j, sum(a[k], k=1..n-1))=1 then ct:=ct+1 else ct:=ct: fi od: a[n]:=ct: od: seq(a[n], n=1..100); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 13 2007`
	CROSSREFS	`Sequence in context: A008644 A008645 A018819 this_sequence A106247 A094909 A029008` `Adjacent sequences: A127367 A127368 A127369 this_sequence A127371 A127372 A127373`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet Mar 30 2007`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 13 2007`

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Last modified December 20 00:58 EST 2009. Contains 171054 sequences.

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