|
| |
|
|
A261678
|
|
Even numbers that are not the sum of two binary palindromes.
|
|
8
|
|
|
|
176, 188, 208, 242, 244, 310, 524, 628, 656, 736, 754, 794, 832, 862, 866, 868, 880, 932, 944, 994, 1000, 1180, 1240, 1308, 1310, 1328, 1342, 1352, 1376, 1408, 1420, 1432, 1440, 1810, 1890, 1922, 1946, 1954, 2126, 2206, 2228, 2262, 2456, 2468, 2498, 2500
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Even numbers that are not the sum of two terms from A006995.
A subsequence of the numbers that are not the sum of three terms from A006995. The two sequences are equal if every odd number is the sum of three terms from A006995 (which is equivalent to the conjecture in A261680). - Chai Wah Wu, Sep 14 2015
|
|
|
LINKS
|
N. J. A. Sloane, Table of n, a(n) for n = 1..10000 [Based on Robert Israel's b-file for A241491]
Aayush Rajasekaran, Jeffrey Shallit, and Tim Smith, Sums of Palindromes: an Approach via Nested-Word Automata, preprint arXiv:1706.10206 [cs.FL], June 30 2017.
|
|
|
MAPLE
|
R:=proc(w) local x, y, z; x:=w; y:=0; for z from 1 to ilog10(x)+1 do y:=10*y+(x mod 10); x:=trunc(x/10); od; y; end:
P:=proc(q) local a, b, k, n, ok; n:=2*q; ok:=1; for k from 1 to trunc(n/2) do a:=convert(k, binary, decimal); b:=convert(n-k, binary, decimal);
if a=R(a) and b=R(b) then ok:=0; break; fi; od; if ok=1 then n; fi; end: seq(P(i), i=1..1250); # Paolo P. Lava, Aug 03 2017
|
|
|
MATHEMATICA
|
lim = 2502; Complement[Most[2 Range@(lim/2)], TakeWhile[DeleteDuplicates@
Sort[Total /@ Tuples[Select[Range@ lim, palQ[#, 2] &], 2]], # < lim &]] (* Michael De Vlieger, Sep 14 2015 *)
|
|
|
CROSSREFS
|
Cf. A006995, A241491 (this sequence divided by 2).
Sequence in context: A172685 A344280 A266058 * A136603 A114824 A305062
Adjacent sequences: A261675 A261676 A261677 * A261679 A261680 A261681
|
|
|
KEYWORD
|
nonn,base
|
|
|
AUTHOR
|
N. J. A. Sloane, Sep 04 2015
|
|
|
STATUS
|
approved
|
| |
|
|
