OFFSET
1,2
COMMENTS
Subsequence of A305231. This sequence excludes for example 4 = (s(4) + (-2)) * (s(4) + (-2)) from that sequence. - David A. Corneth, Apr 15 2019
LINKS
David A. Corneth, Table of n, a(n) for n = 1..17624
Viorel Nitica, Andrei Török, About Some Relatives of Palindromes, arXiv:1908.00713 [math.NT], 2019.
Viorel Niţică, Jeroz Makhania, About the Orbit Structure of Sequences of Maps of Integers, Symmetry (2019), Vol. 11, No. 11, 1374.
EXAMPLE
The sum of the digits of 90 is 9 and (9+21)*reversal(9+21) = 30*3 = 90, so 90 is in the sequence.
The sum of the digits of 2268 is 18 and (18 + 18)*reversal(18 + 18) = 36*63 = 2268, so 2268 is in the sequence.
MATHEMATICA
okQ[k_] := Module[{s, j}, s = Total[IntegerDigits[k]]; For[j = 0, j<k, j++, If[(s+j)IntegerReverse[s+j] == k, Print["k = ", k , ", j = ", j]; Return[ True]]]; False]; Reap[Do[If[okQ[k], Sow[k]], {k, 1, 4275}]][[2, 1]] (* Jean-François Alcover, Mar 17 2019 *)
PROG
(PARI) isok(k) = {my(s = sumdigits(k)); fordiv(k, d, if ((d>=s) && (k/d == fromdigits(Vecrev(digits(d)))), return (1)); ); return (0); } \\ Michel Marcus, Mar 13 2019
(PARI) upto(n) = {my(res = List([1, 10, 40, 81, 90]), m = 0); for(i = 10, 10*sqrtint(n), revi = fromdigits(Vecrev(digits(i))); if(revi <= i && i * revi <= n, m = i; listput(res, i * revi); ) ); q = #res; for(i = 1, #q, for(j = 1, logint(n \ res[i], 10), listput(res, res[i]*10^j); ) ); listsort(res, 1); res } \\ David A. Corneth, Apr 15 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Viorel Nitica, Mar 12 2019
EXTENSIONS
Name clarified by David A. Corneth, Apr 15 2019
STATUS
approved