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 A229018 Primes of the form (3*x + 2)*2^x - 1. 1
 31, 223, 1279, 3276799, 14680063, 420906795007, 2357352929951743, 32326824857489154029020587706017980088319, 173918694842377447266238495093237679339055972614143 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also primes of the form W(n) + W(n+1) + 1 where W(n) and W(n+1) are consecutive Woodall numbers. The n-th Woodall number = n*2^n-1. LINKS K. D. Bajpai, Table of n, a(n) for n = 1..19 Wikipedia, Woodall number EXAMPLE a(2) = 223: for x=4: R= x*2^x-1 = 4*2^4-1 = 63 and S= (x+1)*2^(x+1)-1 = 5*2^5-1 = 159. R+S+1 = 63+159+1 = 223 which is prime. MAPLE KD:= proc() local a, b, d; a:= x*2^x-1; b:=(x+1)*2^(x+1)-1; d:=a+b+1; if isprime(d) then RETURN(d): fi; end: seq(KD(), x=1..1000); MATHEMATICA Select[Table[(3*x + 2)*2^x - 1, {x, 200}], PrimeQ] (* T. D. Noe, Sep 20 2013 *) CROSSREFS Cf. A003261, A072669. Sequence in context: A001136 A256172 A142939 * A036335 A075931 A142440 Adjacent sequences: A229015 A229016 A229017 * A229019 A229020 A229021 KEYWORD nonn AUTHOR K. D. Bajpai, Sep 11 2013 STATUS approved

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Last modified August 3 05:44 EDT 2024. Contains 374875 sequences. (Running on oeis4.)