Search: id:A120094
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%I A120094
%S A120094 7,15,31,63,81,127,239,255,470,511
%N A120094 Rows of Pascal's triangle which contain no terms numerically adjacent 
               to odd primes (the 1's at either end are of course numerically adjacent 
               to the even prime 2).
%C A120094 Apart from the (2^i-1)-th rows, there are no obvious divisibility properties 
               that would explain the coincidence. '1' is the 0-th row.
%e A120094 The 7th, 15th, 31st, ... (2^i-1)-th rows are all included as pascal's 
               triangle only contains odd terms, thus all numerically adjacent terms 
               are even.
%o A120094 (PARI) for(n=2,1000,for(k=1,n\2,ok=1;c=n!/k!/(n-k)!;if(ispseudoprime(c+1)||ispseudoprime(c-1),
               ok=0;break;));if(ok,print(n)))
%Y A120094 Sequence in context: A139597 A117747 A137196 this_sequence A078485 A159695 
               A014001
%Y A120094 Adjacent sequences: A120091 A120092 A120093 this_sequence A120095 A120096 
               A120097
%K A120094 nonn
%O A120094 0,1
%A A120094 Phil Carmody (pc+oeis(AT)asdf.org), Aug 15 2006

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