login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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: A212946 A172685 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 23 06:48 EDT 2019. Contains 328335 sequences. (Running on oeis4.)