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A323510
a(n) = 1 if A005179(n) < A037019(n), 0 otherwise; characteristic function of extraordinary numbers, A072066.
2
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, 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, 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
OFFSET
1
FORMULA
a(n) = [A005179(n) < A037019(n)], where [ ] is the Iverson bracket.
a(A072066(n)) = 1.
PROG
(PARI)
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
A323510(n) = { forstep(k = A037019(n)-1, 1, -1, if(numdiv(k)==n, return(1))); (0); }; \\ Slow, use the program below.
(PARI) A323510(n) = (A005179(n) < A037019(n)); \\ Uses the program given in A005179.
CROSSREFS
Cf. also A323509.
Sequence in context: A187946 A330549 A342019 * A044938 A072401 A064873
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jan 18 2019
STATUS
approved