A235028 Fixed points of A235027.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 17, 18, 20, 21, 24, 25, 27, 28, 30, 31, 32, 34, 35, 36, 40, 42, 45, 48, 49, 50, 51, 54, 56, 60, 62, 63, 64, 68, 70, 72, 73, 75, 80, 81, 84, 85, 90, 93, 96, 98, 100, 102, 105, 107, 108, 112, 119, 120, 124, 125

Offset

1,3

Comments

The first 20 terms are equal with A057890, after which a(21)=25, while A057890(21)=27. On the other hand, 33 is the first term which occurs in A057890 but does not occur here.

If terms x and y are included, then also their product x*y is included. If term x is included, then 2^k * x is also included. The sequence contains also all primes in A016041 and their mutual multiples. However, in addition to that, there are also terms like 143 = 11*13, where A235027 will map the factors to each other (as their binary expansions '1011' and '1101' are mirror images of each other), even although neither of them is present in A016041. (These latter kind of primes are in A074832).

Please use the "graph" link to see how the terms get rarer.

Links

Antti Karttunen, Table of n, a(n) for n = 1..1897

Prog

(Scheme, with Antti Karttunen's IntSeq-library)
(define A235028 (FIXED-POINTS 1 0 A235027))

Crossrefs

The primes in this sequence: A016041.

Cf. A074832, A235027, A235030, A235145, A057890.

Sequence in context: A366378 A108549 A045779 * A062014 A164707 A057890

Adjacent sequences: A235025 A235026 A235027 * A235029 A235030 A235031

Keyword

nonn,base

Author

Antti Karttunen, Jan 02 2014

Status

approved