This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A139083 #12 Jun 28 2025 17:55:23
%S A139083 3,5,7,9,7,9,15,17,11,13,14,16,15,5,19,33,19,21,23,7,5,25,26,28,27,29,
%T A139083 31,33,31,33,63,35,5,7,9,41,39,5,8,46,43,45,47,9,7,49,50,52,51,5,7,57,
%U A139083 55,7,12,10,5,61,62,64,63,9,71,69,7,69,71,7,5,73,79,81,75,5,7,11,9,81
%N A139083 a(n) = (smallest prime-power among the largest powers of each prime dividing n) + (smallest prime-power among the largest powers of each prime dividing (n+1)).
%C A139083 The largest powers of each prime dividing 44 are 2^2 and 11^1. The least of these is 2^2 =4. The largest powers of each prime dividing 45 are 3^2 and 5^1. The least of these is 5^1 = 5. So a(44) = 4 + 5 = 9.
%F A139083 a(n) = A034684(n) + A034684(n+1). [_Franklin T. Adams-Watters_, Apr 09 2009]
%t A139083 f[{a_,b_}]:=a^b;a[n_]:=Min[f/@FactorInteger[n]]+Min[f/@FactorInteger[n+1]];Array[a,78] (* _James C. McMahon_, Jun 28 2025 *)
%o A139083 Contribution from _Franklin T. Adams-Watters_, Apr 09 2009: (Start)
%o A139083 (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 A139083 vector(80,i,minpp(i)+minpp(i+1)) (End)
%Y A139083 Cf. A139081, A139084.
%K A139083 nonn
%O A139083 1,1
%A A139083 _Leroy Quet_, Apr 07 2008
%E A139083 More terms from _Franklin T. Adams-Watters_, Apr 09 2009