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A139084 a(n) = (smallest prime-power among the largest powers dividing n of each prime dividing n) * (smallest prime-power among the largest powers dividing (n+1) of each prime dividing (n+1)). 2

%I

%S 2,6,12,20,10,14,56,72,18,22,33,39,26,6,48,272,34,38,76,12,6,46,69,75,

%T 50,54,108,116,58,62,992,96,6,10,20,148,74,6,15,205,82,86,172,20,10,

%U 94,141,147,98,6,12,212,106,10,35,21,6,118,177,183,122,14,448,320,10,134

%N a(n) = (smallest prime-power among the largest powers dividing n of each prime dividing n) * (smallest prime-power among the largest powers dividing (n+1) of each prime dividing (n+1)).

%C The largest powers dividing 44 of each prime dividing 44 are 2^2 and 11^1. The least of these is 2^2 =4. The largest powers dividing 45 of each prime dividing 45 are 3^2 and 5^1. The least of these is 5^1 = 5. So a(44) = 4 * 5 = 20.

%F a(n) = A034684(n) * A034684(n+1). [From _Franklin T. Adams-Watters_, Apr 09 2009]

%o Contribution from _Franklin T. Adams-Watters_, Apr 09 2009: (Start)

%o (PARI) minpp(n)=local(m,r,pp);if(n==1,1,m=factor(n);r=m[1,1]^m[1,2];for(i=2,matsize(m)[1],pp=m[i,1]^m[i,2];if(pp<r,r=pp));r)

%o vector(80,i,minpp(i)*minpp(i+1)) (End)

%Y Cf. A139082, A139083.

%K nonn

%O 1,1

%A _Leroy Quet_, Apr 07 2008

%E More terms from _Franklin T. Adams-Watters_, Apr 09 2009

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Last modified May 21 21:43 EDT 2022. Contains 353929 sequences. (Running on oeis4.)