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 A296211 a(n) = 1 if sigma(n)-1 is a prime, 0 otherwise. 3
 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1 COMMENTS Characteristic function of A248792, numbers n such that sigma(n) - 1 is a prime. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(1) = 0; for n > 1, a(n) = A010051(A000203(n)-1) = A010051(A039653(n)). a(n) >= A010051(n). PROG (Scheme) (define (A296211 n) (if (= 1 n) 0 (A010051 (+ -1 (A000203 n))))) CROSSREFS Cf. A000203, A010051, A039653, A248792 (positions of ones), A296091, A296212. Sequence in context: A288861 A030190 A157658 * A123506 A051105 A284929 Adjacent sequences:  A296208 A296209 A296210 * A296212 A296213 A296214 KEYWORD nonn AUTHOR Antti Karttunen, Dec 07 2017 STATUS approved

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Last modified October 16 05:23 EDT 2019. Contains 328043 sequences. (Running on oeis4.)