cp's OEIS Frontend

A132435 Composite integers n with two prime factors nearly equidistant from the integer part of the square root of n.

%I A132435 #12 Jan 03 2021 11:19:57
%S A132435 4,6,9,10,14,22,25,35,49,55,65,77,85,91,119,121,143,169,187,209,221,
%T A132435 247,253,289,299,319,323,361,377,391,407,437,493,527,529,551,589,629,
%U A132435 667,697,703,713,841,851,899,943,961,989,1073,1081,1147,1189
%N A132435 Composite integers n with two prime factors nearly equidistant from the integer part of the square root of n.
%C A132435 An integer n is included if, for some value y >= 0: n = A007918(A000196(n) + y) * A007918(A000196(n) - y) Or: n = nextprime(sqrtint(n) + y) * nextprime(sqrtint(n) - y) Where "nextprime(x)" is the smallest prime number >= to x and "sqrtint(z)" is the integer part of the square root of z.
%C A132435 Has many terms in common with A078972. - _Bill McEachen_, Dec 24 2020
%H A132435 Michel Marcus, <a href="/A132435/b132435.txt">Table of n, a(n) for n = 1..3406</a>
%e A132435 25 = nextprime(5 + 0) * nextprime(5 - 0) = 5 * 5 = 25
%e A132435 35 = nextprime(5 + 1) * nextprime(5 - 1) = 7 * 5 = 35
%e A132435 119 = nextprime(10 + 4) * nextprime(10 - 4) = 17 * 7 = 119
%o A132435 (PARI) bal(x,y) = nextprime(sqrtint(x)+y) * nextprime(sqrtint(x)-y);
%o A132435 findbal(x) = local(z,y); z=sqrtint(x); while( 0<=z, y=bal(x,z); if(y==x, print1(x", ");break;); z--;);
%o A132435 for (n=1,1200, findbal(n));
%Y A132435 Cf. A007918, A000196, A078972.
%K A132435 nonn
%O A132435 1,1
%A A132435 _Andrew S. Plewe_, Nov 13 2007