OFFSET
1,1
COMMENTS
If an element of this sequence is odd, it must be of the form a(n)=8+p^3, else it is a(n)=p^3+q^3 with two primes p>q>2. - M. F. Hasler, Apr 13 2008
LINKS
M. F. Hasler and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 284 terms from Hasler)
FORMULA
EXAMPLE
2^3+3^3=35=a(1), 2^3+5^3=133=a(2), 3^3+5^3=152=a(3), 2^3+7^3=351=a(4).
MATHEMATICA
Select[Sort[ Flatten[Table[Prime[n]^3 + Prime[k]^3, {n, 15}, {k, n - 1}]]], # <= Prime[15^3] &]
PROG
(PARI) isA030078(n)=n==round(sqrtn(n, 3))^3 && isprime(round(sqrtn(n, 3))) \\ M. F. Hasler, Apr 13 2008
(PARI) isA120398(n)={ n%2 & return(isA030078(n-8)); n<35 & return; forprime( p=ceil( sqrtn( n\2+1, 3)), sqrtn(n-26.5, 3), isA030078(n-p^3) & return(1))} \\ M. F. Hasler, Apr 13 2008
(PARI) for( n=1, 10^6, isA120398(n) & print1(n", ")) \\ - M. F. Hasler, Apr 13 2008
(PARI) list(lim)=my(v=List()); lim\=1; forprime(q=3, sqrtnint(lim-8, 3), my(q3=q^3); forprime(p=2, min(sqrtnint(lim-q3, 3), q-1), listput(v, p^3+q3))); Set(v) \\ Charles R Greathouse IV, Mar 31 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Tanya Khovanova, Jul 24 2007
STATUS
approved