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A283974 Numbers n for which A002487(n-1) AND A002487(n) > 0 where AND is bitwise-and (A004198).

%I A283974 #13 Mar 23 2017 11:43:52
%S A283974 2,5,6,7,8,11,14,17,18,19,20,23,24,25,26,29,30,31,32,34,35,38,39,40,
%T A283974 41,42,43,44,45,46,47,50,51,52,53,54,55,56,57,58,59,62,63,65,66,67,68,
%U A283974 69,70,71,72,73,74,75,76,77,79,80,81,82,83,86,89,92,95,96,97,98,101,104,107,110,111,112,113,114,116,117,118,119,120
%N A283974 Numbers n for which A002487(n-1) AND A002487(n) > 0 where AND is bitwise-and (A004198).
%C A283974 Numbers n such that the binary representations of A002487(n-1) and A002487(n) have at least one 1-bit in a common shared position.
%H A283974 Antti Karttunen, <a href="/A283974/b283974.txt">Table of n, a(n) for n = 1..10000</a>
%H A283974 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%t A283974 a[0] = 0; a[1] = 1; a[n_] := If[EvenQ@ n, a[n/2], a[(n - 1)/2] + a[(n + 1)/2]]; Flatten@ Position[Table[BitAnd[a[n - 1], a@ n], {n, 120}], k_ /; k > 0] (* _Michael De Vlieger_, Mar 22 2017 *)
%o A283974 (Scheme, with _Antti Karttunen_'s IntSeq-library)
%o A283974 (define A283974 (NONZERO-POS 1 1 A283988))
%o A283974 (PARI) A(n) = if(n<2, n, if(n%2, A(n\2) + A((n + 1)/2), A(n/2)));
%o A283974 D(n) = if(n<1, 1, sum(k=0, n, binomial(n + k - 1, 2*k)%2))
%o A283974 for(n=1, 120, if(bitor(A(n - 1), A(n)) != D(n), print1(n, ", "))) \\ _Indranil Ghosh_, Mar 23 2017
%Y A283974 Cf. A283973 (complement).
%Y A283974 Cf. A002487, A004198, A007306, A283986, A283987.
%Y A283974 Positions of nonzeros in A283988.
%K A283974 nonn,base
%O A283974 1,1
%A A283974 _Antti Karttunen_, Mar 21 2017