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A064924
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If n is prime then a(n) = n; for the subsequent nonprime positions a(n + k) = (k+1)*n; then at the next prime position a new subsequence begins.
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4
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2, 3, 6, 5, 10, 7, 14, 21, 28, 11, 22, 13, 26, 39, 52, 17, 34, 19, 38, 57, 76, 23, 46, 69, 92, 115, 138, 29, 58, 31, 62, 93, 124, 155, 186, 37, 74, 111, 148, 41, 82, 43, 86, 129, 172, 47, 94, 141, 188, 235, 282, 53, 106, 159, 212, 265, 318, 59, 118, 61, 122, 183, 244
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| A064920(a(n)) = n.
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 2..10000
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FORMULA
| a(n) = A007917(n) * (A064722(n) + 1)
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EXAMPLE
| a(7) = A007917(7) * (A064722(7) + 1) = 7 * (0 + 1) = 7; a(8) = A007917(8) * (A064722(8) + 1) = 7 * (1 + 1) = 14; a(9) = A007917(9) * (A064722(9) + 1) = 7 * (2 + 1) = 21; a(10) = A007917(10) * (A064722(10) + 1) = 7 * (3 + 1) = 28; a(11) = 11.
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MATHEMATICA
| a[n_?PrimeQ] := n; a[n_] := NextPrime[n, -1]*(n - NextPrime[n, -1] + 1); Table[a[n], {n, 2, 64}] (* From Jean-François Alcover, Sep 19 2011 *)
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PROG
| (PARI) { for (n=2, 10000, if (isprime(n), a=m=n; k=2, a=k*m; k++); write("b064924.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 29 2009]
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CROSSREFS
| A064920, A064923, A007917, A064722, A064919.
Sequence in context: A043547 A064919 A064923 * A196330 A055944 A073740
Adjacent sequences: A064921 A064922 A064923 * A064925 A064926 A064927
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KEYWORD
| nice,nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 14 2001
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