A046486 Numbers k such that the sum of the first k palindromes is a palindrome.

1, 2, 3, 12, 16, 47, 314

Offset

1,2

Links

Table of n, a(n) for n=1..7.

Patrick De Geest, World!Of Numbers

Example

a(n)=47 so 1+2+3+...+373+383 (47 terms) = 7557.

Mathematica

palQ[n_] := Reverse[x = IntegerDigits[n]] == x; t = Select[Range[25000], palQ[#] &]; Flatten[Rest[Position[Accumulate[t], _?palQ]]] (* Jayanta Basu, Jun 26 2013 *)
Position[Accumulate[Select[Range[100000], PalindromeQ]], _?PalindromeQ] // Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 31 2020 *)

Crossrefs

Cf. A002113, A046487, A046488.

Sequence in context: A345362 A333319 A047163 * A073452 A112976 A100570

Adjacent sequences: A046483 A046484 A046485 * A046487 A046488 A046489

Keyword

nonn,hard,base

Author

Patrick De Geest, Sep 15 1998

Status

approved