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 A285329 a(n) = A013928(A007947(n)). 7
 0, 1, 2, 1, 3, 4, 5, 1, 2, 6, 7, 4, 8, 9, 10, 1, 11, 4, 12, 6, 13, 14, 15, 4, 3, 16, 2, 9, 17, 18, 19, 1, 20, 21, 22, 4, 23, 24, 25, 6, 26, 27, 28, 14, 10, 29, 30, 4, 5, 6, 31, 16, 32, 4, 33, 9, 34, 35, 36, 18, 37, 38, 13, 1, 39, 40, 41, 21, 42, 43, 44, 4, 45, 46, 10, 24, 47, 48, 49, 6, 2, 50, 51, 27, 52, 53, 54, 14, 55, 18, 56, 29, 57, 58, 59, 4, 60, 9, 20, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS For n > 1, a(n) gives the (one-based) index of the column where n is located in array A284311, or respectively, index of the row where n is in A284457. A008479 gives the other index. LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A013928(A007947(n)). Other identities. For all n >= 0: If A008683(n) <> 0 [when n is squarefree, A005117], a(n) = A013928(n), otherwise a(n) = a(A285328(n)). a(A019565(n)) = A064273(n). PROG (Scheme, with memoization-macro definec) (definec (A285329 n) (if (not (zero? (A008683 n))) (A013928 n) (A285329 (A285328 n)))) (define (A285329 n) (A013928 (A007947 n))) (Python) from operator import mul from sympy import primefactors from sympy.ntheory.factor_ import core def a007947(n): return 1 if n<2 else reduce(mul, primefactors(n)) def a013928(n): return sum([1 for i in xrange(1, n) if core(i) == i]) print [a013928(a007947(n)) for n in xrange(1, 101)] # Indranil Ghosh, Apr 18 2017 CROSSREFS Cf. A008479 (the other index). Cf. A005117, A007947, A008683, A013928, A019565, A064273, A087207, A285328. Cf. array A284311 (A284457). Sequence in context: A325324 A241745 A210040 * A289023 A085985 A285107 Adjacent sequences:  A285326 A285327 A285328 * A285330 A285331 A285332 KEYWORD nonn AUTHOR Antti Karttunen, Apr 17 2017 STATUS approved

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Last modified October 22 17:39 EDT 2019. Contains 328319 sequences. (Running on oeis4.)