%I #5 Dec 05 2013 19:57:05
%S 11,113,311,11311,113111,11131111,11113111,1113111107,7011113111,
%T 111311110717,717011113111,111311110717,71701111311131,
%U 1311131111071703,307170111131113123,32131113111107170309,9030717011113111312321
%N a(1) = 11, then least prime beginning with the digit reversal of the previous term.
%e a(3) = 311 because the reversal of a(2) = 113 is 311 and 311 is prime.
%e a(4) = 11311 because the reversal of a(3) = 311 is 113, which is already in the list. The next smallest prime that starts with 113 is 11311.
%p reverse := proc (nn) local n,m; m := 0; n := nn; while (n > 0) do m := m*10 + irem(n,10,'n'); od; m; end:
%p a := proc(n,m) option remember; global currSet; local currN, i, origN, j; if n = 0 then currSet := {m}; return m; end if; currN := reverse(a(n - 1,m)); if (not (evalb(currN in currSet))) then if (isprime(currN)) then currSet := currSet union {currN}; return currN; end if; end if; origN := currN; j := 1; while (true) do origN := 10 * origN; currN := origN; i := 0; while i < (10^j) do if (isprime(currN) and (not evalb(currN in currSet))) then currSet := currSet union {currN}; return currN; end if; currN := currN + 1; i := i + 1; end do; j := j + 1; end do; return currN; end proc; (Deugau)
%Y Cf. A090543, A111462.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, Aug 04 2005
%E More terms from Chris Deugau (deugaucj(AT)uvic.ca), Nov 04 2005