A073879 a(1) = 1, a(n) = smallest number not included earlier such that a(1)+...+a(n) is a palindrome.

1, 2, 3, 5, 11, 22, 33, 24, 10, 20, 30, 41, 40, 50, 21, 60, 31, 70, 51, 81, 80, 61, 71, 91, 90, 112, 110, 220, 330, 231, 440, 550, 121, 660, 341, 770, 451, 671, 880, 561, 781, 891, 882, 100, 200, 300, 410, 400, 500, 210, 600, 310, 700, 510, 810, 800, 610, 710, 910

Offset: 1

Author

Amarnath Murthy, Aug 16 2002

Keywords

• base
• nonn
• look

Links

• Ivan Neretin, Table of n, a(n) for n = 1..8323 (all terms before the sum exceeds 10^12)

Crossrefs

Cf. A073880.

Programs

Mathematica

seq={1}; Do[s=Total[seq]; k=1; While[MemberQ[seq, k] || !PalindromeQ[s+k], k++]; AppendTo[seq, k], {i,1,50}]; seq (* Amiram Eldar, Dec 04 2018 *)

PARI

ispal(n)={my(v=digits(n));for(i=1, #v\2, if(v[i]<>v[#v+1-i], return(0))); 1}
seq(n)={my(v=vector(n), M=Map(), t=0); for(n=1, n, for(k=1, oo, if(!mapisdefined(M,k) && ispal(k+t), mapput(M,k,1); v[n]=k; t+=k; break))); v} \\ Andrew Howroyd, Dec 04 2018

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Jun 24 2003