A162854 Take the binary representation of n. Reduce by half the number of digits in every run (completely of either 0's or 1's) of an even number of digits. Double the number of digits in every run of an odd number of digits in the binary representation of n (where the added digits have the same value that makes up the rest of the run's digits). a(n) = the decimal equivalent of the result.

3, 12, 1, 6, 51, 4, 63, 192, 27, 204, 25, 2, 19, 252, 3, 12, 771, 108, 13, 102, 819, 100, 831, 64, 11, 76, 9, 126, 1011, 12, 1023, 3072, 51, 3084, 385, 54, 435, 52, 447, 3264, 411, 3276, 409, 50, 403, 3324, 51, 4, 259, 44, 5, 38, 307, 36, 319, 4032, 507, 4044, 505

Offset

1,1

Comments

Clarification: The consecutive "runs" (mentioned in the definition) alternate between those completely of 1's and those completely of 0's.

This sequence is not a permutation of the positive integers.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

152 in binary is: 10011000 There is a run of one 1, followed by a run of two 0's, followed by a run of two 1's, followed by a run of three 0's. We halve the two runs of two digits each to one digit each; and we double the number of digits (with a 1) in the first run of one 1, and double the number of digits (with 0's) in the last run of three 0's, to get 1101000000. a(152) is the decimal equivalent of this, which is 832.

Maple

rerun := proc(L) if nops(L) mod 2 = 0 then [op(1..nops(L)/2, L)] ; else [op(L), op(L)] ; fi; end: Lton := proc(L) local i; add( op(i, L)*2^(i-1), i=1..nops(L)) ; end: A162854 := proc(n) local strt, en, L, dgs, i; strt := 1; en := -1; L := [] ; dgs := convert(n, base, 2) ; for i from 2 to nops(dgs) do if op(i, dgs) <> op(i-1, dgs) then en := i-1 ; L := [op(L), op(rerun([op(strt..en, dgs)])) ] ; strt := i; fi; od: en := nops(dgs) ; L := [op(L), op(rerun([op(strt..en, dgs)])) ] ; Lton(L) ; end: seq(A162854(n), n=1..100) ; # R. J. Mathar, Aug 01 2009

Mathematica

Table[FromDigits[Flatten[If[EvenQ[Length[#]], Take[#, Length[#]/2], Join[ #, #]]&/@ Split[IntegerDigits[n, 2]]], 2], {n, 60}] (* Harvey P. Dale, May 30 2018 *)

Crossrefs

Sequence in context: A354568 A072117 A162853 * A342787 A110121 A321710

Adjacent sequences: A162851 A162852 A162853 * A162855 A162856 A162857

Keyword

base,nonn

Author

Leroy Quet, Jul 14 2009

Extensions

Extended beyond a(16) by R. J. Mathar, Aug 01 2009

Status

approved