A180508 - OEIS

%I #6 Mar 30 2012 18:35:54

%S 3,8,46,50,76,100,144,266,274,334,504,516,526,566,670,726,756,810,836,

%T 844,1064,1086,1164,1250,1300,1714,1740,1800,1826,1834,1946,1950,2014,

%U 2194,2220,2440,2450,2466,2494,2560,2610

%N Numbers k such that k^2 + 1 = p*q, p and q primes and | p-q | <= k.

%C |p - q| = k for k = 3, 8, 144.

%e 46 is in the sequence because 46^2 + 1 = 29*73, and 73-29 = 44 < 46.

%p with(numtheory):for n from 1 to 4000 do: x:=n^2+1:y:=factorset(x):yy:=bigomega(x):if

%p   yy=2 and (y[2]-y[1] < n or y[2]-y[1] = n) then printf(`%d, `,n):else fi:od:

%Y Cf. A134406 A027862 A134407 A002522 A005574.

%K nonn

%O 1,1

%A _Michel Lagneau_, Jan 20 2011