%I #7 Nov 20 2020 15:35:29
%S 0,4,8,12,56,910,1354,5798,9111312,13555756,5799911910,
%T 911131313551354,1355575757995798,579991191191113139111312,
%U 9111313135513551355575713555756,135557575799579957999119115799911910
%N a(0) = 0; a(n) is obtained by incrementing each digit of a(n-1) by 4.
%C In A061511-A061522, A061746-A061750 when the incremented digit exceeds 9 it is written as a 2-digit string. So 9+1 becomes the 2-digit string 10, etc.
%H Harvey P. Dale, <a href="/A061517/b061517.txt">Table of n, a(n) for n = 0..27</a>
%t NestList[FromDigits[Flatten[IntegerDigits/@(IntegerDigits[#]+4)]]&,0,20] (* _Harvey P. Dale_, Nov 20 2020 *)
%K base,nonn
%O 0,2
%A _Amarnath Murthy_, May 08 2001
%E More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001