OFFSET
1,2
COMMENTS
Numbers of the form 2^m*(4^k-1)/3 and, simultaneously, of the form 3*j+1, for k>0, j,m>=0.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
seq[max_] := Module[{kmax = Floor[Log[4, 3*max+1]], s = {}, s1, odd}, Do[odd = (4^k-1)/3; s1 = 2^Range[0, Floor[Log2[max/odd]]] * odd; s = Join[s, s1], {k, 1, kmax}]; Select[Union[s], Mod[#, 3] == 1 &]]; seq[1500000] (* Amiram Eldar, Aug 31 2024 *)
PROG
(PARI) for(n=1, 300000, o=3*n/2^valuation(n, 2)+1; b=ispower(o); if(b&&b%2==0&&round(sqrtn(o, b/2))==4&&(n-1)%3==0, print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Ralf Stephan, Nov 19 2010
EXTENSIONS
More terms from Amiram Eldar, Aug 31 2024
STATUS
approved