A323510 a(n) = 1 if A005179(n) < A037019(n), 0 otherwise; characteristic function of extraordinary numbers, A072066.

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

Links

Antti Karttunen, Table of n, a(n) for n = 1..107520

Index entries for characteristic functions

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. A005179, A037019, A072066.

Cf. also A323509.

Sequence in context: A187946 A330549 A342019 * A044938 A072401 A064873

Adjacent sequences: A323507 A323508 A323509 * A323511 A323512 A323513

Keyword

nonn

Author

Antti Karttunen, Jan 18 2019

Status

approved