Respostas

A melhor resposta!
2014-03-26T14:55:34-03:00
An=a1+(n-1)r, 18 passa a ser 19, e 272 passa a ser 271 (aqui vc está procurando somente os números impares)
271=19+(n-1)2 
271-19=2(n-1) 
252=2(n-1) 
252/2=n-1 
126=n-1 
126+1=n 
n=127
2 5 2
2014-03-26T15:02:01-03:00
 19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99,101,103,105,107,109,111,113,115,117,119,121,123,125,127,129,131,133,135,137,139,141,143,145,147,149,151,153,155,157,159,161,163,165,167,169,171,173,175,177,179,181,183,185,187,189,191,193,195,197,199,201,203,205,207,209,211,223,215,217,219,221,223,225,227,229,231,233,235,237,239,241,243,245,247,249,251,253,255,257,259,261,263,265,267,269,271 =  127 números primos