A123112 Smallest number k such that k^n is equal to the sum of n consecutive primes, or 1 if it does not exist.
2, 6, 11, 12, 3, 18, 81, 90, 81, 942, 1773, 2532, 77, 1866, 637, 126, 1725, 56, 2695, 128, 3647, 6960, 1295, 7180, 10809, 430, 10233, 2944, 3269, 160, 10919, 9068, 40925, 22066, 10763, 558, 1403, 4344, 2943, 8894, 9813, 9308, 4691, 20516, 13801, 8056, 36425
Offset: 1
Crossrefs
Cf. A162160.
Programs
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Maple
isnp := proc(x,n) local xbar,p,psum,i ; xbar := floor(x/n) ; p := array(1..n) ; p[1] := nextprime(xbar) ; for i from 2 to n do p[i] := nextprime(p[i-1]) ; od ; psum := add(p[i],i=1..n) ; while psum >= x do if psum = x then RETURN(true) ; elif p[1] = 2 then RETURN(false) ; else psum := psum-p[n] ; for i from n to 2 by -1 do p[i] := p[i-1] ; od ; p[1] := prevprime(p[1]) ; psum := psum+p[1] ; fi ; od ; RETURN(false) ; end; A123112 := proc(n) local k ; k := 1 ; while true do if isnp(k^n,n) then RETURN(k) ; else k := k+1 ; fi ; od ; end; for n from 1 to 30 do print(A123112(n)) ; od ; # R. J. Mathar, Jan 13 2007
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PARI
print1(2); for(n=2, 10, k=n%2; until(s==t, k+=2; t=k^n; s=0; q=t\n; p=q+1; for(i=0, n-1, if(s*n
Extensions
More terms from R. J. Mathar, Jan 13 2007
a(17)-a(26) from Max Alekseyev
a(27)-a(43) from Donovan Johnson, Nov 17 2008
a(44)-a(47) from Jens Kruse Andersen, Jul 23 2014
Comments