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Search: id:A084662
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| A084662 |
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a(1) = 4; a(n) = a(n-1) + gcd(a(n-1), n). |
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+0
7
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| 4, 6, 9, 10, 15, 18, 19, 20, 21, 22, 33, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 69, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 141, 144, 145, 150, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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Eric S. Rowland, A simple prime-generating recurrence, Abstracts Amer. Math. Soc., 29 (No. 1, 2008), p. 50 (Abstract 1035-11-986).
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
Eric S. Rowland, A simple prime-generating recurrence.
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MAPLE
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S := 4; f := proc(n) option remember; global S; if n=1 then S else f(n-1)+igcd(n, f(n-1)); fi; end;
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MATHEMATICA
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f[n_] := f[n-1] + GCD[n, f[n-1]]; f[1]=4
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CROSSREFS
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Cf. A084663, A106108 and other sequences mentioned in A106108.
Adjacent sequences: A084659 A084660 A084661 this_sequence A084663 A084664 A084665
Sequence in context: A005659 A010462 A028957 this_sequence A137167 A122492 A133234
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KEYWORD
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nonn
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AUTHOR
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Matthew Frank (mfrank(AT)wopr.wolfram.com) on behalf of the 2003 New Kind of Science Summer School, Jul 15 2003
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