A089308 - OEIS

%I #4 Dec 05 2013 19:56:35

%S 1,2,3,3,4,5,4,5,6,10,5,6,7,8,9,6,7,8,9,10,11,7,8,9,10,11,12,14,8,9,

%T 10,11,12,14,15,16,9,10,11,12,13,14,15,16,21,10,11,12,13,14,15,17,18,

%U 19,20,11,12,13,14,15,16,17,18,19,20,21,12,13,14,15,16,17,18,19,20,21,22,23

%N Triangle read by rows, in which n-th row contains n numbers starting with n and in increasing order such that the product of the terms + 1 gives the smallest such prime.

%C It is not always the case that the first n-1 terms are n,n+1, n+2, ... 2n-2 etc. and then the last term chosen to yield a prime. The choice of the terms is the one that yields the least prime.

%e 1

%e 2 3

%e 3 4 5

%e 4 5 6 10

%e 5 6 7 8 9

%e ...

%e a(22)..a(28)=7,8,9,10,11,12,14 is the strictly increasing sequence that yields the smallest prime A089307(7)=9313921 of the form 7*n2*n3*..*n7+1, 7<n2<...<n7.

%Y Cf. A089307.

%K nonn,tabl

%O 1,2

%A _Amarnath Murthy_, Nov 01 2003

%E More terms from _Hugo Pfoertner_, Apr 06 2004