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Search: id:A102863
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| A102863 |
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a(n)=1 if at least one of the first n primes is a divisor of the sum of the first n primes; otherwise a(n)=0. |
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+0
3
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| 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(2)=0 because none of the first 2 primes (2, 3) is a divisor of 2+3; a(5)=1 because among the first 5 primes (namely, 2,3,5,7,11) there are divisors of 2+3+5+7+11=28.
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MAPLE
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with(numtheory): a:=proc(n) if nops(factorset(sum(ithprime(k), k=1..n)) intersect {seq(ithprime(j), j=1..n)}) >0 then 1 else 0 fi end: seq(a(n), n=1..130); (Deutsch)
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CROSSREFS
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A105783(n) gives number of primes among the first n primes that are divisors of the sum of the first n primes.
Sequence in context: A071025 A162549 A115788 this_sequence A131483 A077052 A133566
Adjacent sequences: A102860 A102861 A102862 this_sequence A102864 A102865 A102866
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Mar 01 2005
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EXTENSIONS
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Edited and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 19 2005
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