OFFSET
1,2
COMMENTS
The sequence of binary reversals that are squares is a permutation of a(n), it begins: 1, 9, 20457529, 143784081, 331130809, 5216450625, 4365905625, 20074072489, 1193532215121, 10036851273801, 38767247532225, 36014509461681, ...
A029983 is a subsequence (after zero). - Antti Karttunen, Dec 20 2013
FORMULA
a(n) = A229766(n)^2.
PROG
(C)
#include <stdio.h>
#include <math.h>
int main() {
unsigned long long n, t, r, sr;
for (n=1; n<(1ULL<<32); n+=2) {
t = n*n;
r = 0;
while (t) r = r*2+(t&1), t >>= 1;
sr = sqrt(r);
if (sr*sr==r) printf("%llu, ", n*n);
}
return 0;
}
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Alex Ratushnyak, Dec 19 2013
STATUS
approved