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A171463
The natural numbers excluding 2 and 3.
0
1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74
OFFSET
1,2
COMMENTS
Numbers k > 0 such that k*(k+1)/2 - 1 is nonprime. - Juri-Stepan Gerasimov, May 04 2010
FORMULA
a(n) = n + [n>1]*2.
MATHEMATICA
Drop[Range[100], {2, 3}] (* Harvey P. Dale, May 05 2018 *)
PROG
(PARI) a(n)=if(n==1, 1, n+2) \\ Charles R Greathouse IV, Sep 02 2011
CROSSREFS
Sequence in context: A114143 A171526 A359740 * A020705 A081313 A227983
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Dec 09 2009, Dec 15 2009
STATUS
approved