Funsters & fansters might be amused by this somewhat unlikely coincidence. I had calculated a couple of hundred terms of a fourth order recurring sequence [it's A005178 in OEIS, if you want details] and was looking for the ranks of apparition of various primes. A 19-digit prime factor of the 53rd term turned up as a substring of the 103rd term! Have a prime time in 7^2 x 41. R. ---------- Forwarded message ---------- Date: Wed, 17 Dec 2008 09:24:06 -0700 (MST) From: Richard Guy <rkg@cpsc.ucalgary.ca> To: Hugh Cowie Williams <williams@math.ucalgary.ca> Subject: You wouldn't believe Hugh, before sending the final (??) version of the quadric file, I decided I'd do a search for larger primes just to see if there were any double ranks. While searching with 3140540902719737029 which is a factor of a(53), I discovered that it's a substring of a(103): 93118232931779128686097911301602920314054090271973702981658870701 ^^^^^^^^^^^^^^^^^^^ R.