This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A029959 #35 Jun 14 2024 11:59:46
%S A029959 0,1,2,3,4,5,6,7,8,9,10,11,12,13,15,30,45,60,75,90,105,120,135,150,
%T A029959 165,180,195,197,211,225,239,253,267,281,295,309,323,337,351,365,379,
%U A029959 394,408,422,436,450,464,478,492,506,520,534,548,562,576,591
%N A029959 Numbers that are palindromic in base 14.
%C A029959 Cilleruelo, Luca, & Baxter prove that this sequence is an additive basis of order (exactly) 3. - _Charles R Greathouse IV_, May 04 2020
%H A029959 John Cerkan, <a href="/A029959/b029959.txt">Table of n, a(n) for n = 1..10000</a>
%H A029959 Javier Cilleruelo, Florian Luca and Lewis Baxter, <a href="https://doi.org/10.1090/mcom/3221">Every positive integer is a sum of three palindromes</a>, Mathematics of Computation, Vol. 87, No. 314 (2018), pp. 3023-3055, <a href="http://arxiv.org/abs/1602.06208">arXiv preprint</a>, arXiv:1602.06208 [math.NT], 2017.
%H A029959 Patrick De Geest, <a href="http://www.worldofnumbers.com/nobase10.htm">Palindromic numbers beyond base 10</a>.
%H A029959 Phakhinkon Phunphayap and Prapanpong Pongsriiam, <a href="https://doi.org/10.13140/RG.2.2.23202.79047">Estimates for the Reciprocal Sum of b-adic Palindromes</a>, 2019.
%H A029959 <a href="/index/Ab#basis_03">Index entries for sequences that are an additive basis</a>, order 3.
%F A029959 Sum_{n>=2} 1/a(n) = 3.6112482... (Phunphayap and Pongsriiam, 2019). - _Amiram Eldar_, Oct 17 2020
%e A029959 195 is DD in base 14.
%e A029959 196 is 100 in base 14, so it's not in the sequence.
%e A029959 197 is 101 in base 14.
%t A029959 palQ[n_, b_:10] := Module[{idn = IntegerDigits[n, b]}, idn == Reverse[idn]]; Select[ Range[0, 600], palQ[#, 14] &] (* _Harvey P. Dale_, Aug 03 2014 *)
%o A029959 (PARI) isok(n) = Pol(d=digits(n, 14)) == Polrev(d); \\ _Michel Marcus_, Mar 12 2017
%o A029959 (Python)
%o A029959 from sympy import integer_log
%o A029959 from gmpy2 import digits
%o A029959 def A029959(n):
%o A029959 if n == 1: return 0
%o A029959 y = 14*(x:=14**integer_log(n>>1,14)[0])
%o A029959 return int((c:=n-x)*x+int(digits(c,14)[-2::-1]or'0',14) if n<x+y else (c:=n-y)*y+int(digits(c,14)[-1::-1]or'0',14)) # _Chai Wah Wu_, Jun 14 2024
%Y A029959 Palindromes in bases 2 through 13: A006995, A014190, A014192, A029952, A029953, A029954, A029803, A029955, A002113, A029956, A029957, A029958.
%K A029959 nonn,base,easy
%O A029959 1,3
%A A029959 _Patrick De Geest_