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A134736
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a(1) = 5; for n >1, a(n) = a(n-1) + gcd(n, a(n-1)).
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8
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5, 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
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refs;
listen;
history;
text;
internal format)
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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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MATHEMATICA
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a[1] = 5; a[n_] := a[n] = a[n-1] + GCD[n, a[n-1]];
RecurrenceTable[{a[1]==5, a[n]==a[n-1]+GCD[n, a[n-1]]}, a, {n, 70}] (* Harvey P. Dale, Nov 24 2018 *)
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PROG
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(Haskell)
a134736 n = a134736_list !! (n-1)
a134736_list =
5 : zipWith (+) a134736_list (zipWith gcd a134736_list [2..])
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CROSSREFS
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See A106108 for other cross-references.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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