|
Search: id:A158789
|
|
|
| A158789 |
|
a(n) = the smallest positive multiple of (2n-1) that contains the binary representation of n in its binary representation and that is a palindrome when written in binary. |
|
+0
1
|
|
| 1, 9, 15, 231, 27, 99, 455, 195, 51, 2565, 189, 2553, 1675, 189, 7163, 15903, 99, 5285, 2553, 10725, 21525, 3483, 495, 17249, 6419, 2805, 30263, 10725, 30039, 6077, 31903, 3591, 195, 1675, 116679, 108843, 2409, 52275, 231, 361741, 38313, 27307, 2805
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
EXAMPLE
|
3 in binary is 11. Checking the multiples of 5 (which is 3*2-1) to determine the 3rd term of the sequence, we have: 1*5 = 5 = 101 in binary, which is a palindrome, but does not contain the substring 11. 2*5 = 10 (decimal) = 1010 in binary, which both does not contain 11 and is not a palindrome. 3*5 = 15 = 1111 in binary, which is a palindrome and does contain the substring 11. So a(3) = 15.
|
|
MAPLE
|
ispal := proc(L) local i; for i from 1 to nops(L)/2 do if op(i, L) <> op(-i, L) then RETURN(false) ; fi; od: RETURN(true) ; end: A158789 := proc(n) local k, adgs, a, ndgs; ndgs := convert(n, base, 2) ; for k from 1 do a := k*(2*n-1) ; adgs := convert(a, base, 2) ; if verify(ndgs, adgs, 'sublist') then if ispal(adgs) then RETURN(a) ; fi; fi; od: end: seq(A158789(n), n=1..55) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2009]
|
|
CROSSREFS
|
Sequence in context: A098146 A124274 A075134 this_sequence A100241 A078794 A093595
Adjacent sequences: A158786 A158787 A158788 this_sequence A158790 A158791 A158792
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Mar 26 2009
|
|
EXTENSIONS
|
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2009
|
|
|
Search completed in 0.002 seconds
|
