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A023515
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a(n) = prime(n)*prime(n-1) - 1.
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9
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1, 5, 14, 34, 76, 142, 220, 322, 436, 666, 898, 1146, 1516, 1762, 2020, 2490, 3126, 3598, 4086, 4756, 5182, 5766, 6556, 7386, 8632, 9796, 10402, 11020, 11662, 12316, 14350, 16636, 17946, 19042, 20710, 22498, 23706, 25590, 27220, 28890
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OFFSET
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1,2
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COMMENTS
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a(1) = 1 assumes the not generally accepted convention prime(0) = 1. - Klaus Brockhaus, Dec 23 2010
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LINKS
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FORMULA
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(End)
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MAPLE
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1, seq(ithprime(n)*ithprime(n-1)-1, n=2..40); # Muniru A Asiru, Apr 27 2019
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MATHEMATICA
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Prepend[Table[Prime@ n Prime[n - 1] - 1, {n, 2, 12}], 1] (* Michael De Vlieger, Nov 10 2015 *)
Join[{1}, Times@@#-1&/@Partition[Prime[Range[40]], 2, 1]] (* Harvey P. Dale, Jul 06 2024 *)
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PROG
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(PARI) a(n) = if(n==1, 1, prime(n)*prime(n-1)-1) \\ Altug Alkan, Nov 10 2015
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CROSSREFS
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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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