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%I #9 Jan 18 2019 20:54:31
%S 0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,
%U 0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1
%N a(n) = 1 if A005179(n) < A037019(n), 0 otherwise; characteristic function of extraordinary numbers, A072066.
%H Antti Karttunen, <a href="/A323510/b323510.txt">Table of n, a(n) for n = 1..107520</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = [A005179(n) < A037019(n)], where [ ] is the Iverson bracket.
%F a(A072066(n)) = 1.
%o (PARI)
%o A037019(n, p=1) = prod(i=1, #f=Vecrev(factor(n)~), prod(j=1, f[i][2], (p=nextprime(p+1))^(f[i][1]-1))); \\ From A037019
%o A323510(n) = { forstep(k = A037019(n)-1, 1, -1, if(numdiv(k)==n, return(1))); (0); }; \\ Slow, use the program below.
%o (PARI) A323510(n) = (A005179(n) < A037019(n)); \\ Uses the program given in A005179.
%Y Cf. A005179, A037019, A072066.
%Y Cf. also A323509.
%K nonn
%O 1
%A _Antti Karttunen_, Jan 18 2019