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!)
A243155 Larger of the two consecutive primes whose positive difference is a cube. 1

%I #13 Jun 06 2014 11:17:17

%S 3,97,367,397,409,457,487,499,691,709,727,751,769,919,937,991,1117,

%T 1171,1201,1381,1447,1531,1567,1579,1741,1831,1987,2011,2161,2221,

%U 2251,2281,2467,2539,2617,2671,2707,2749,2851,2887,2917,3019,3049,3217,3229,3457,3499

%N Larger of the two consecutive primes whose positive difference is a cube.

%C Observation: All the terms in this sequence, after a(1), are the larger of the two consecutive primes which have positive difference either 2^3 or 4^3.

%C Superset of A031927 as the sequence contains for example numbers like 89753, 107441, 288647,.. (with gaps of 4^3...) that are not in A031927. - _R. J. Mathar_, Jun 06 2014

%H K. D. Bajpai, <a href="/A243155/b243155.txt">Table of n, a(n) for n = 1..10000</a>

%e 97 is prime and appears in the sequence because 97 - 89 = 8 = 2^3.

%e 397 is prime and appears in the sequence because 397 - 389 = 8 = 2^3.

%p A243155:= proc() local a; a:=evalf((ithprime(n+1)-ithprime(n))^(1/3)); if a=floor(a) then RETURN (ithprime(n+1)); fi; end: seq(A243155 (), n=1..100);

%t n = 0; Do[t = Prime[k] - Prime[k - 1]; If[IntegerQ[t^(1/3)], n++; Print[n, " ", Prime[k]]], {k, 2, 15*10^4}]

%o (PARI) s=[]; forprime(p=3, 4000, if(ispower(p-precprime(p-1), 3), s=concat(s, p))); s \\ _Colin Barker_, Jun 03 2014

%Y Cf. A031927, A123996, A118590, A001632.

%K nonn

%O 1,1

%A _K. D. Bajpai_, May 31 2014

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 15 19:43 EDT 2024. Contains 373410 sequences. (Running on oeis4.)