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A064799
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Sum of n-th prime number and n-th composite number.
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5
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6, 9, 13, 16, 21, 25, 31, 34, 39, 47, 51, 58, 63, 67, 72, 79, 86, 89, 97, 103, 106, 113, 118, 125, 135, 140, 143, 149, 153, 158, 173, 179, 186, 189, 200, 203, 211, 218, 223, 230, 237, 241, 253, 256, 261, 264, 277, 291, 296, 299, 305, 313, 316, 327, 334, 341
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) = A000040(n) + A002808(n). [From Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Dec 13 2009]
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REFERENCES
| Ivan Grischenko, ivansasha(AT)mtu-net.ru, private communication.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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FORMULA
| a(n) = prime(n)+composite(n)
a(n) = A171639(n+1). [From Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Dec 13 2009]
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EXAMPLE
| E.g. a(1)=6 because first prime is 2 and first composite is 4. a(2)=9 because p(2)=3 and c(2)=6. Et cetera.
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PROG
| (PARI) nextComp(n)= { if (!isprime(n), return(n)); return(n + 1) } { p=1; c=3; for (n=1, 1000, p=nextprime(p + 1); c=nextComp(c + 1); write("b064799.txt", n, " ", p + c) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 25 2009]
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CROSSREFS
| Sequence in context: A106218 A118521 A095213 * A030499 A181428 A171575
Adjacent sequences: A064796 A064797 A064798 * A064800 A064801 A064802
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KEYWORD
| nonn,easy
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AUTHOR
| Konstantin Knop (Konstantin(AT)Knop.com), Oct 21 2001
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EXTENSIONS
| More terms from Larry Reeves (larryr(AT)acm.org), Nov 12 2001
OFFSET changed from 0,1 to 1,1 by Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 25 2009
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