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A123754
Positive numbers of the form 4*n^2 - 1 which are not semiprimes.
1
3, 63, 99, 195, 255, 399, 483, 575, 675, 783, 1023, 1155, 1295, 1443, 1599, 1935, 2115, 2303, 2499, 2703, 2915, 3135, 3363, 3843, 4095, 4355, 4623, 4899, 5475, 5775, 6083, 6399, 6723, 7055, 7395, 7743, 8099, 8463, 8835, 9215, 9603, 9999, 10815
OFFSET
1,1
COMMENTS
Positive numbers of the form 4*n^2 - 1 which are semiprimes can be found in A037074.
Or, all positive products of the form A014076(i)*[A014076(i)+-2], duplicates removed. - R. J. Mathar, Aug 08 2007
LINKS
FORMULA
Equals ( A000466 - {-1} ) - A001358. - R. J. Mathar, Aug 08 2007
MATHEMATICA
Select[4*(Range[54])^2-1, Not[PrimeQ[Sqrt[(#+ 1)]-1] && PrimeQ[Sqrt[(#+1)]+1]]&]
Select[4*Range[100]^2-1, PrimeOmega[#]!=2&] (* Harvey P. Dale, Jul 24 2016 *)
CROSSREFS
Sequence in context: A333041 A323726 A087886 * A048354 A046181 A151993
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Nov 16 2006
EXTENSIONS
Edited by N. J. A. Sloane, Aug 03 2007
STATUS
approved