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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 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.)