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a(1) = 1; for n >= 1, a(n+1) = smallest number not occurring earlier such that a(n)*a(n+1) + 1 is a palindrome.
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%I #11 Sep 24 2018 16:53:14

%S 1,2,3,7,14,10,11,21,23,32,5,13,17,29,9,6,20,8,4,19,18,28,27,22,16,34,

%T 98,135,51,146,110,101,100,102,73,220,56,131,67,43,15,12,26,38,35,181,

%U 202,50,31,215,54,111,1891,386,45,153,130,80,125,84,398,251,70,150,68

%N a(1) = 1; for n >= 1, a(n+1) = smallest number not occurring earlier such that a(n)*a(n+1) + 1 is a palindrome.

%e a(51)=54; 54*1 + 1 = palindrome 55 but 1 occurs already at a(1); next 54*11 + 1 = 595 but 11 occurs already at a(7); next 54*14 + 1 = 757 but 14 occurs at a(5); next 54*17 + 1 = 919 but 17 occurs at a(13); ...; finally 54*111 + 1 = 5995 and 111 did not yet occur so 111 is included as next term a(52).

%Y Cf. A081941, A082271.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Apr 02 2003, Apr 14 2003

%E More terms from _Patrick De Geest_, Jun 09 2003

%E Edited by _N. J. A. Sloane_ at the suggestion of _Andrew S. Plewe_, Jun 09 2007