OFFSET
1,21
COMMENTS
a(n)=min (abs(n-k) : where k runs through the prime powers)
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
MATHEMATICA
nn = 100; pp = Select[Range[2, Prime[1 + PrimePi[nn]]], Length[FactorInteger[#]] == 1 &]; Table[Min[Abs[n - pp]], {n, nn}] (* T. D. Noe, Mar 14 2012 *)
CROSSREFS
There are four different sequences which may legitimately be called "prime powers": A000961 (p^k, k >= 0), A246655 (p^k, k >= 1), A246547 (p^k, k >= 2), A025475 (p^k, k=0 and k >= 2). When you refer to "prime powers", be sure to specify which of these you mean. - N. J. A. Sloane, Mar 24 2018
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Mar 08 2003
STATUS
approved