[math-fun] d x e = r and now concatenate e and r
Hello Math-Fun and SeqFans, still a few hours to go in 2007, in Brussels, Belgium -- and thus time for our last (uninteresting) seq of the year! S=1,11,22,24,28,216,318,324,416,424,624,728,756,848,864, 936,954,1144,1248,1296,1378,13104,26104,27108,27216,... All integers of S are the concatenation of e and r, r being the "r"esult of (d x e) and d being the last "d"igit of the previous integer. Integer a(n+1) must be bigger than a(n) but the gap between a(n) and a(n+1) must be the smallest possible one. No integer of S can end with a zero. Example: Start with a(1)=1 then d=1 and, obviously, e=1 and r=1 --> S=1,11,... Now d=1 again and we must take e=2 ; thus r=2 and --> S=1,11,22,... Now d=2 and the closest integer to the last one (22) can be found with e=2 ; thus r=4 and --> S=1,11,22,24,... Etc. In other words, we multiply the last digit of a(n) by something, we concatenante the result immediately after this something, and we look for the smallest integer resulting in this concatenation but bigger than a(n). Voilà! Cheers, happy 2008, mind the headaches! É.
participants (1)
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Eric Angelini