cp's OEIS Frontend

A077760 Numbers which in at least two ways are the product of two distinct numbers with the same digits (leading zeros are forbidden).

%I A077760 #21 Jun 11 2025 23:40:36
%S A077760 101556,121968,124012,133875,144648,172900,185472,226800,352170,
%T A077760 433755,2096640,3779136,4264416,5166504,5333680,5448960,5651919,
%U A077760 5894784,5955264,5983936,6003088,6174630,6197724,6324318,6351840,6429600,6494400,6514060,6794424,6874560,7064496
%N A077760 Numbers which in at least two ways are the product of two distinct numbers with the same digits (leading zeros are forbidden).
%H A077760 David A. Corneth, <a href="/A077760/b077760.txt">Table of n, a(n) for n = 1..10408</a> (terms <= 2*10^10)
%e A077760 101556 = 156*651 = 273*372; 2096640 = 1092*1920 = 1365*1536.
%o A077760 (PARI) {for(n=100, 6500000,  my(k=logint(n,100), f=divisors(n), v=[]); for(h=1, matsize(f)[2], if(10^k<f[h]&& f[h]<10^(k+1), v=concat(v, f[h]))); my(b=matsize(v)[2]); if(b>1, my(w=[]); for(i=1, b, my(s=[], a=v[i]); while(a>0, my(d=divrem(a, 10)); a=d[1]; s=concat(d[2], s)); w=concat(w, [vecsort(s)])); my(c=0); for(i=1, b-1, for(j=i+1, b, if(c<2&&w[i]==w[j], if(v[i]*v[j]==n, if(c==1, print1(n, ", "); c=2, c=1)))))))}
%Y A077760 Cf. A000037, A072443.
%K A077760 nonn,base
%O A077760 1,1
%A A077760 _Klaus Brockhaus_, Nov 14 2002
%E A077760 Offset changed to 1 by and more terms from _David A. Corneth_, Sep 08 2024
%E A077760 Name corrected by _Sean A. Irvine_, Jun 11 2025