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A322860 If n is practical (in A005153), a(n) = 1, otherwise a(n) = 0. 2
1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1

COMMENTS

Characteristic function of practical numbers, A005153.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

FORMULA

a(n) = [A030057(n) > n], where [ ] is the Iverson bracket.

PROG

(PARI) A322860(n) = { if((n%2), return(1==n)); my(p=1, f=factor(n)); for(i=2, #f~, if((f[i, 1] > (1+(p*=sigma(f[i-1, 1]^f[i-1, 2])))), return(0))); (1); }; \\ After M. F. Hasler's code in A005153

CROSSREFS

Cf. A005153, A030057, A225559 (partial sums).

Sequence in context: A322585 A326956 A341629 * A178225 A264739 A257170

Adjacent sequences:  A322857 A322858 A322859 * A322861 A322862 A322863

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 31 2018

STATUS

approved

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Last modified May 18 05:01 EDT 2021. Contains 343994 sequences. (Running on oeis4.)