OFFSET
0,11
COMMENTS
This sequence coincides with A088601 for n <= 301, but differs at n=302.
Although A088601 and this sequence agree for a large number of terms, because of their importance they warrant separate entries.
Cilleruelo and Luca prove that a(n) <= 3 (in fact they prove this for any fixed base g>=5). - Danny Rorabaugh, Feb 26 2016
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 0..10000
Javier Cilleruelo and Florian Luca, Every positive integer is a sum of three palindromes, arXiv preprint arXiv:1602.06208 [math.NT], 2016.
William D. Banks, Every natural number is the sum of forty-nine palindromes, INTEGERS 17 (2016), 9 pp.
James Grime and Brady Haran, Every Number is the Sum of Three Palindromes (2018), Numberphile video
PROG
(PARI) ispal(n)=my(d=digits(n)); d==Vecrev(d);
a(n)=my(L=n\2, d, e); if(ispal(n), return(1)); d=[1]; while((e=fromdigits(d))<=L, if(ispal(n-e), return(2)); my(k=#d, i=(k+1)\2); while(i&&d[i]==9, d[i]=0; d[k+1-i]=0; i--); if(i, d[i]++; d[k+1-i]=d[i], d=vector(#d+1); d[1]=d[#d]=1)); 3; \\ Charles R Greathouse IV, Nov 12 2018
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Sep 02 2015
STATUS
approved