cp's OEIS Frontend

A334661 Numbers k such that k*sod(k) and k+sod(k) are both palindromes, where sod(k) denotes the sum of digits of k (A007953).

%I A334661 #26 May 16 2020 01:45:36
%S A334661 0,1,2,3,124,829,186373637,186454637,187272737,195454547,23212121199,
%T A334661 23302120299,1230303030288,1312121212098,1320303030198,1321121211198,
%U A334661 1321203021198,1321211121198,1330121210298,1330203020298,1330211120298,1330301030298,2130303030279
%N A334661 Numbers k such that k*sod(k) and k+sod(k) are both palindromes, where sod(k) denotes the sum of digits of k (A007953).
%C A334661 For the first 2729 terms, most of them have digit sum 33. The only terms a(n) for n <= 2729 for which the digit sum is not 33 are for n = 1,...,10, 716, 2194, 2195. - _Chai Wah Wu_, May 15 2020
%H A334661 Chai Wah Wu, <a href="/A334661/b334661.txt">Table of n, a(n) for n = 1..2729</a>
%e A334661 The sum of digits of 829 is 19 and 829*19 = 15751 and 829+19 = 848 are palindromes, so 829 is a term.
%t A334661 Select[Range[0, 999], (s = Plus @@ IntegerDigits[#]; PalindromeQ[# s] && PalindromeQ[# + s]) &]
%o A334661 (PARI) ispal(n) = my(d=digits(n)); d == Vecrev(d);
%o A334661 isok(m) = my(s=sumdigits(m)); ispal(m*s) && ispal(m+s); \\ _Michel Marcus_, May 08 2020
%Y A334661 Intersection of A229549 and A229545.
%Y A334661 Cf. A007953, A334533.
%K A334661 nonn,base
%O A334661 1,3
%A A334661 _Giovanni Resta_, May 07 2020