

A090178


a(1) = 2; for n > 1, a(n) = n + prime(n1).


6



2, 4, 6, 9, 12, 17, 20, 25, 28, 33, 40, 43, 50, 55, 58, 63, 70, 77, 80, 87, 92, 95, 102, 107, 114, 123, 128, 131, 136, 139, 144, 159, 164, 171, 174, 185, 188, 195, 202, 207, 214, 221, 224, 235, 238, 243, 246, 259, 272, 277, 280, 285, 292, 295, 306, 313, 320, 327
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OFFSET

1,1


COMMENTS

Sum of index n and the corresponding nth term of noncomposite numbers (A008578).
Does n > 2 exist such that n*prime(n1)/(n+prime(n1)), i.e., A164931(n)/a(n) is an integer?  Jaroslav Krizek, Aug 31 2009


REFERENCES

M. Feenstra, P. J. Carter and C. P. Harding, The Ultimate I.Q. Book, Wardlock, see p. 99.


LINKS



FORMULA



EXAMPLE

a(2) = 2 + prime(1) = 4; a(5) = 5 + prime(4) = 12; a(9) = 9 + prime(8) = 28.


MATHEMATICA



PROG

(Magma) [n + NthPrime(n1): n in [1..58] ]; // Klaus Brockhaus, Sep 09 2009


CROSSREFS

The published version (A048171) is said to be incorrect.


KEYWORD

nonn


AUTHOR

Pab Ter (pabrlos(AT)yahoo.com), May 29 2004


EXTENSIONS

Definition corrected, second comment and example edited by Klaus Brockhaus, Sep 09 2009


STATUS

approved



