OFFSET
2,4
COMMENTS
LINKS
EXAMPLE
a(4) = -1: 2^4 = 16, (13 + 17 - 32)/2 = -1;
a(5) = 2: 2^5 = 32, (31 + 37 - 64)/2 = 2;
a(6) = 0: 2^6 = 64, (61 + 67 - 128)/2 = 0.
MAPLE
a:= (p-> (nextprime(p)+prevprime(p))/2-p)(2^n):
seq(a(n), n=2..75); # Alois P. Heinz, Jan 29 2021
MATHEMATICA
Array[(NextPrime[2^#] + NextPrime[2^#, -1] - 2^(# + 1))/2 &, 60, 2] (* Michael De Vlieger, Aug 07 2022 *)
PROG
(PARI) for(k=2, 71, my(p2=2^k, pp=precprime(p2), pn=nextprime(p2)); if(print1((pp+pn-2*p2)/2", ")))
CROSSREFS
KEYWORD
sign
AUTHOR
Hugo Pfoertner, Jan 29 2021
EXTENSIONS
Name made more precise by Peter Luschny, Aug 08 2022
STATUS
approved