The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A046497 Palindromes expressible as sum of 2 consecutive palindromes. 3
 1, 3, 5, 7, 9, 11, 33, 55, 77, 99, 121, 212, 232, 252, 272, 292, 393, 414, 434, 454, 474, 494, 595, 616, 636, 656, 676, 696, 797, 818, 838, 858, 878, 898, 999, 2112, 2332, 2552, 2772, 2992, 3993, 4114, 4334, 4554, 4774, 4994, 5995, 6116, 6336, 6556, 6776, 6996, 7997, 8118, 8338, 8558 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Contains all palindromes such that the middle digit is odd (if number of digits is odd) or middle two digits are odd (if number of digits is even) and all other digits are even; also palindromes where the first and last digits are odd (but not 1) and all other digits are 9. - Robert Israel, Nov 12 2018 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 P. De Geest, World!Of Numbers EXAMPLE 999 = 494 + 505. MAPLE ispali:= proc(n) local L; L:= convert(n, base, 10); L = ListTools:-Reverse(L) end proc: digrev:= proc(n) local L;   L:= convert(n, base, 10);   add(L[-i]*10^(i-1), i=1..nops(L)) end proc: N:=5; Pals:= \$0..9: for d from 2 to N do   q:= p;   if d::even then     m:= d/2;     Pals:= Pals, seq(n*10^m + digrev(n), n=10^(m-1)..10^m-1);   else     m:= (d-1)/2;     Pals:= Pals, seq(seq(n*10^(m+1)+y*10^m+digrev(n), y=0..9), n=10^(m-1)..10^m-1);   fi od: Pals:= [Pals]: select(ispali, Pals[1..-2]+Pals[2..-1]); # Robert Israel, Nov 12 2018 MATHEMATICA palQ[n_] := Reverse[x = IntegerDigits[n]] == x; Select[Total /@ Partition[Select[Range[3500], palQ], 2, 1], palQ] (* Jayanta Basu, Jun 26 2013 *) nextPalindrome[n_]:=Module[{k=n+1}, While[!PalindromeQ[k], k++]; k]; s={}; Do[If[PalindromeQ[n], sum =n +  nextPalindrome[n]; If[PalindromeQ[sum], AppendTo[s, sum]]], {n, 0, 10000}]; s (* Amiram Eldar, Nov 10 2018 *) CROSSREFS Cf. A002113. Sequence in context: A092361 A029950 A061507 * A061512 A083964 A131628 Adjacent sequences:  A046494 A046495 A046496 * A046498 A046499 A046500 KEYWORD nonn,base AUTHOR Patrick De Geest, Sep 15 1998 EXTENSIONS a(1)=1 inserted by Alois P. Heinz, Nov 13 2018 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.

Last modified August 7 17:44 EDT 2020. Contains 336278 sequences. (Running on oeis4.)