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 A195896 Numbers of the form 2*p-1 or 3*p-1 where p is 1 or a prime. 1
 1, 2, 3, 5, 8, 9, 13, 14, 20, 21, 25, 32, 33, 37, 38, 45, 50, 56, 57, 61, 68, 73, 81, 85, 86, 92, 93, 105, 110, 117, 121, 122, 128, 133, 140, 141, 145, 157, 158, 165, 176, 177, 182, 193, 200, 201, 205, 212, 213, 217, 218, 225, 236, 248, 253, 261, 266, 273, 277, 290, 297, 301, 302, 308 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..64. FORMULA Union of A076274 and A112773. EXAMPLE a(1)=1 because p=1 and 2*1 - 1 = 1; a(2)=2 because p=1 and 3*1 - 1 = 2; a(3)=3 because p=2 and 2*2 - 1 = 3; a(4)=5 because p=2 and 3*3 - 1 = 5 or p=3 and p=2 and 3*2 - 1 = 5; a(5)=8 because p=3 and 3*3 - 1 = 8. MAPLE isA195896 := proc(n) for p in {(n+1)/2, (n+1)/3} do if type(p, 'integer') then if isprime(p) or p = 1 then return true; end if; end if; end do; false ; end proc: for n from 1 to 400 do if isA195896(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Oct 15 2011 MATHEMATICA Union[Flatten[Join[{1, 2}, {2#-1, 3#-1}&/@Prime[Range[50]]]]] (* Harvey P. Dale, Mar 27 2015 *) CROSSREFS Cf. A196127, A008578. Sequence in context: A189086 A256656 A035422 * A058237 A251599 A270151 Adjacent sequences: A195893 A195894 A195895 * A195897 A195898 A195899 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Sep 24 2011 STATUS approved

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Last modified December 7 23:30 EST 2023. Contains 367662 sequences. (Running on oeis4.)