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 A229687 Odd squares whose binary reversal is also a square. 3
 1, 9, 20457529, 143784081, 331130809, 4365905625, 5216450625, 20074072489, 1193532215121, 10036851273801, 36014509461681, 38767247532225, 41413201925481, 155991531977649, 320642706437001, 2543173099393689, 2696589987547401, 4665141483989281, 87463589042698969 (list; graph; refs; listen; history; text; internal format)
 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 LINKS FORMULA a(n) = A229766(n)^2. PROG (C) #include #include 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; } (Scheme) (define (A229687 n) (A000290 (A229766 n))) ;; Antti Karttunen, Dec 20 2013 CROSSREFS Cf. A000290, A029983, A074832, A229766. Sequence in context: A273234 A259159 A131678 * A029983 A225775 A154110 Adjacent sequences:  A229684 A229685 A229686 * A229688 A229689 A229690 KEYWORD nonn,base AUTHOR Alex Ratushnyak, Dec 19 2013 STATUS approved

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Last modified December 10 23:29 EST 2019. Contains 329910 sequences. (Running on oeis4.)