A342699 Numbers k such that A342698(k) = k.

0, 1, 3, 7, 9, 12, 15, 17, 19, 24, 25, 28, 31, 33, 35, 39, 48, 49, 51, 56, 57, 60, 63, 65, 67, 71, 79, 96, 97, 99, 103, 112, 113, 115, 120, 121, 124, 127, 129, 131, 135, 143, 153, 159, 192, 193, 195, 199, 204, 207, 224, 225, 227, 231, 240, 241, 243, 248, 249

Offset: 1

Author

Rémy Sigrist, Mar 18 2021

Keywords

• nonn
• base

Comments

Equivalently, these are the numbers k such that each bit in the binary representation of k is next to a bit with the same value (and we consider that the first bit is next to the last bit). Hence, all terms of A033015 belong to this sequence.

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A033015, A342698.

Programs

PARI

is(n) = my (w=#binary(n)); sum(k=0, w-1, ((bittest(n, (k-1)%w)+bittest(n, k%w)+bittest(n, (k+1)%w))>=2) * 2^k)==n