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A075191
Numbers k such that k^3 is an interprime = average of two successive primes.
12
4, 12, 16, 26, 28, 36, 48, 58, 66, 68, 74, 78, 102, 106, 112, 117, 124, 126, 129, 130, 148, 152, 170, 174, 184, 189, 190, 192, 224, 273, 280, 297, 321, 324, 369, 372, 373, 399, 408, 410, 421, 426, 429, 435, 447, 449, 450, 470, 475, 496, 504, 507, 531, 537
OFFSET
1,1
COMMENTS
Interprimes are in A024675, even interprimes are in A072568, odd interprimes are in A072569 n^2 as interprimes are in A075190, n^4 as interprimes are in A075192, n^5 as interprimes are in A075228, n^6 as interprimes are in A075229, n^7 as interprimes are in A075230, n^8 as interprimes are in A075231, n^9 as interprimes are in A075232, n^10 as interprimes are in A075233, a(n) such that a(n)^n = smallest interprime (of the form a^n) are in A075234.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Alois P. Heinz)
EXAMPLE
4 is a term because 4^3 = 64 is the average of two successive primes 61 and 57.
MAPLE
s := 3: for n from 2 to 1000 do if prevprime(n^s)+nextprime(n^s)=2*n^s then print(n) else; fi; od;
MATHEMATICA
Select[ Range[548], 2#^3 == PrevPrim[ #^3] + NextPrim[ #^3] &]
n3ipQ[n_]:=Mean[{NextPrime[n^3], NextPrime[n^3, -1]}]==n^3; Select[ Range[ 600], n3ipQ] (* Harvey P. Dale, Oct 05 2017 *)
Select[Surd[Mean[#], 3]&/@Partition[Prime[Range[8*10^6]], 2, 1], IntegerQ] (* Harvey P. Dale, Apr 07 2023 *)
PROG
(PARI) is(n)=n=n^3; nextprime(n)+precprime(n)==2*n \\ Charles R Greathouse IV, Aug 25 2014
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 09 2002
EXTENSIONS
Edited by Robert G. Wilson v Sep 14 2002
STATUS
approved