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 A102863 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. 3
 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; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = 0 if and only if n is in A013916. - Robert Israel, Jan 04 2017 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 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. MAPLE 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); # Emeric Deutsch # alternative: N:= 500: # to get the first N terms A:= Vector(N): S:= 2: P:= 2: p:= 2: A[1]:= 1: for n from 2 to N do   p:= nextprime(p);   S:= S+p; P:= P*p;   if igcd(S, P) > 1 then A[n]:= 1 fi od: convert(A, list); # Robert Israel, Jan 04 2017 MATHEMATICA a[n_] := Module[{pp = Prime[Range[n]], t}, t = Total[pp]; Boole[AnyTrue[pp, Divisible[t, #]&]]]; Array[a, 100] (* Jean-François Alcover, Jun 16 2020 *) CROSSREFS A105783(n) gives number of primes among the first n primes that are divisors of the sum of the first n primes. Cf. A013916, A136443. Sequence in context: A195062 A229940 A179761 * A131483 A077052 A133566 Adjacent sequences:  A102860 A102861 A102862 * A102864 A102865 A102866 KEYWORD easy,nonn AUTHOR Giovanni Teofilatto, Mar 01 2005 EXTENSIONS Edited and extended by Emeric Deutsch, Apr 19 2005 STATUS approved

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Last modified April 21 04:42 EDT 2021. Contains 343146 sequences. (Running on oeis4.)