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 A200746 Completely multiplicative function with a(prime(k)) = prime(k)*prime(k-1), a(2) = 2. 3
 1, 2, 6, 4, 15, 12, 35, 8, 36, 30, 77, 24, 143, 70, 90, 16, 221, 72, 323, 60, 210, 154, 437, 48, 225, 286, 216, 140, 667, 180, 899, 32, 462, 442, 525, 144, 1147, 646, 858, 120, 1517, 420, 1763, 308, 540, 874, 2021, 96, 1225, 450, 1326, 572, 2491, 432, 1155, 280, 1938 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(n) = n * A064989(n). MATHEMATICA a200746[n_Integer] := Block[{f, p, a},   f[x_] := Transpose@FactorInteger[x];   p[x_] := Which[     x == 1, 1,     x == 2, 2,     True, x NextPrime[x, -1]];   a[x_] := Times @@ Power[p /@ First[f[x]], Last[f[x]]]; a /@ Range[n]]; a200746[57] (* Michael De Vlieger, Dec 19 2014 *) PROG (PARI) a(n)=local(fm=factor(n)); prod(k=1, matsize(fm)[1], (fm[k, 1]*if(fm[k, 1]==2, 1, precprime(fm[k, 1]-1)))^fm[k, 2]) (Scheme, with memoization-macro definec) (definec (A200746 n) (if (<= n 2) n (* n (A064989 n)))) ;; Antti Karttunen, Dec 18 2014 CROSSREFS Cf. A064989, A108951, A191002. Sequence in context: A226569 A111807 A069914 * A130190 A110346 A095754 Adjacent sequences:  A200743 A200744 A200745 * A200747 A200748 A200749 KEYWORD nonn,mult,look AUTHOR Franklin T. Adams-Watters, Nov 25 2011 STATUS approved

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Last modified July 23 14:44 EDT 2021. Contains 346259 sequences. (Running on oeis4.)