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

2, 5, 6, 7, 8, 11, 14, 17, 18, 19, 20, 23, 24, 25, 26, 29, 30, 31, 32, 34, 35, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 62, 63, 65, 66, 67, 68, 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

Offset: 1

Author

Antti Karttunen, Mar 21 2017

Keywords

• nonn
• base

Comments

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.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to binary expansion of n

Crossrefs

Cf. A283973 (complement).

Cf. A002487, A004198, A007306, A283986, A283987.

Positions of nonzeros in A283988.

Programs

Mathematica

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 *)

PARI

A(n) = if(n<2, n, if(n%2, A(n\2) + A((n + 1)/2), A(n/2)));
D(n) = if(n<1, 1, sum(k=0, n, binomial(n + k - 1, 2*k)%2))
for(n=1, 120, if(bitor(A(n - 1), A(n)) != D(n), print1(n, ", "))) \\ Indranil Ghosh, Mar 23 2017