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Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!) A284261 a(n) = A284258(n) - A284258(A003961(n)). 3 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1 (list; graph; refs; listen; history; text; internal format) OFFSET 1,429 COMMENTS The first 2 occurs at n = 429 = 3*11*13. A003961(429) = 1105 = 5*13*17. The first 3 occurs at n = 7293 = 3*11*13*17. A003961(7293) = 20995 = 5*13*17*19. LINKS Antti Karttunen, Table of n, a(n) for n = 1..10001 FORMULA a(n) = A284258(n) - A284258(A003961(n)). a(n) = A001221(A284254(n)) - A001221(A284254(A003961(n))). MATHEMATICA Table[If[n == 1, 0, Subtract @@ Map[Count[#, d_ /; d > First[#]^2] &@ FactorInteger[#][[All, 1]] &, {n, Times @@ Map[#1^#2 & @@ # &, FactorInteger[n] /. {p_, e_} /; e > 0 :> {Prime[PrimePi@ p + 1], e}] - Boole[n == 1]}]], {n, 120}] (* Michael De Vlieger, Mar 24 2017 *) PROG (Scheme) (define (A284261 n) (- (A284258 n) (A284258 (A003961 n)))) CROSSREFS Cf. A001221, A003961, A284254, A284258, A252459. Sequence in context: A353495 A302047 A044940 * A037825 A278701 A188300 Adjacent sequences: A284258 A284259 A284260 * A284262 A284263 A284264 KEYWORD nonn AUTHOR Antti Karttunen, Mar 24 2017 EXTENSIONS Secondary offset corrected by Antti Karttunen, Dec 15 2017 STATUS approved

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Last modified August 18 13:06 EDT 2024. Contains 375269 sequences. (Running on oeis4.)