OFFSET
1,1
COMMENTS
A subset of these, 2089, 4481, 7057, 15193, 15641, etc., allows this representation in more than two ways (See A206606).
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10808 (first 500 terms from Seiichi Manyama, terms <= 8*10^7)
EXAMPLE
The prime 17 can be written 1^3 + 4^2 as well as 2^3 + 3^2.
MAPLE
isA162930 := proc(n) if isprime(n) then wa := 0 ; for y from 1 to n/2 do if issqr(n-y^3) then if n -y^3 > 0 then wa := wa+1 ; fi; fi; od: RETURN( wa>1) ; else false; fi; end:
for i from 1 to 2700 do if isA162930 ( ithprime(i)) then printf("%d, ", ithprime(i)) ; fi; od: # R. J. Mathar, Jul 21 2009
MATHEMATICA
lst={}; Do[Do[AppendTo[lst, n^2+m^3], {n, 2*5!}], {m, 2*5!}]; lst=Sort[lst]; lst2={}; Do[If[lst[[n]]==lst[[n+1]]&&PrimeQ[lst[[n]]], AppendTo[lst2, lst[[n]]]], {n, Length[lst]-1}]; lst2;
PROG
(PARI) upto(n) = {my(res = List(), v = vector(n), i, j, i2); for(i = 1, sqrtint(n), i2 = i^2; for(j = 1, sqrtnint(n - i^2, 3), v[i2 + j^3]++)); forprime(p = 2, n, if(v[p] > 1, listput(res, p))); kill(v); res} \\ David A. Corneth, Jun 20 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jul 17 2009
EXTENSIONS
Slightly edited by R. J. Mathar, Jul 21 2009
STATUS
approved