The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A107990 Primes representing areas of cube faces where the integer part of the cube's volume is also prime. 1

%I #10 Dec 04 2018 20:45:25

%S 2,3,5,43,89,113,131,163,457,467,509,541,587,739,773,887,1109,1123,

%T 1201,1307,1319,1409,1613,1741,1747,1787,1979,2063,2069,2459,2467,

%U 2671,2689,2741,2789,3187,3203,3539,3547,3557,3643,3823,3917,3989,4021,4441,4447

%N Primes representing areas of cube faces where the integer part of the cube's volume is also prime.

%C If the area of a single face of the cube is p, the volume is V=(sqrt(p))^3, and we look for cases where floor(V) and p are both prime.

%F {p in A000040: floor(p^(2/3)) in A000040}.

%e If the area of the cube is the prime p = 5, the side length is sqrt(5), the volume is 5^(3/2) = 11.18033..., and the truncated (floor) value of the volume is 11, a prime, which puts the prime p=5 to the sequence.

%o (PARI) g(n) = forprime(x=2,n,y=floor(sqrt(x)^3);if(isprime(y),print1(x, ",")))

%Y Cf. A107989.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Jun 13 2005

%E Offset set to 1, example expanded - _R. J. Mathar_, Sep 16 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 3 09:48 EDT 2024. Contains 373057 sequences. (Running on oeis4.)