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A064799 Sum of n-th prime number and n-th composite number. 7
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; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = A000040(n) + A002808(n). - Jaroslav Krizek, Dec 13 2009

REFERENCES

Ivan Grischenko, ivansasha(AT)mtu-net.ru, private communication.

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = prime(n) + composite(n).

a(n) = A171639(n+1). - Jaroslav Krizek, Dec 13 2009

EXAMPLE

a(1)=6 because the first prime is 2 and the first composite is 4; 2 + 4 = 6

a(2)=9 because prime(2)=3 and composite(2)=6; 3 + 6 = 9.

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) ) } \\ Harry J. Smith, Sep 25 2009

CROSSREFS

Sequence in context: A242874 A284800 A242295 * A236763 A030499 A181428

Adjacent sequences:  A064796 A064797 A064798 * A064800 A064801 A064802

KEYWORD

nonn,easy

AUTHOR

Konstantin Knop (Konstantin(AT)Knop.com), Oct 21 2001

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Nov 12 2001

Offset changed from 0 to 1 by Harry J. Smith, Sep 25 2009

STATUS

approved

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Last modified August 20 03:33 EDT 2019. Contains 326139 sequences. (Running on oeis4.)