A129623 -id:A129623 - cp's OEIS frontend

A072443 Nonsquares which are the product of two numbers with the same digits (leading zeros are forbidden).

252, 403, 574, 736, 765, 976, 1008, 1207, 1300, 1458, 1462, 1612, 1729, 1855, 1944, 2268, 2296, 2430, 2668, 2701, 2944, 3154, 3478, 3627, 3640, 4032, 4275, 4606, 4930, 5092, 5605, 5848, 6624, 6786, 7663, 8722, 11110, 12240, 13390, 13552, 14560, 14803, 15750, 16074

Offset: 1

N. J. A. Sloane, Nov 11 2002

			12*21 = 252 = 12*21, 403 = 13*31, 574 = 14*41, etc

P. Vaderlind, R. K. Guy and L. C. Larsen, The Inquisitive Problem Solver, Math. Assoc. Am., 2002, Problem P185.

Michael S. Branicky, Table of n, a(n) for n = 1..10000

A077760 is a subsequence.

Cf. A076750, A129623.

{for(n=100,15000,k=floor(log(n)/log(100)); f=divisors(n); v=[]; for(h=1,matsize(f)[2], if(10^k1, w=[]; for(i=1,b,s=[]; a=v[i]; while(a>0,d=divrem(a,10); a=d[1]; s=concat(d[2],s)); w=concat(w,[vecsort(s)])); c=0; for(i=1,b-1, for(j=i+1,b,if(c<1&&w[i]==w[j],if(v[i]*v[j]==n,print1(n,","); c=1))))))}

from math import isqrt
from sympy import divisors
def ok(n): return isqrt(n)**2Michael S. Branicky, Sep 08 2024

Extended by Klaus Brockhaus, Nov 12 2002

a(42) and beyond from Michael S. Branicky, Sep 08 2024

cp's OEIS Frontend

A072443 Nonsquares which are the product of two numbers with the same digits (leading zeros are forbidden).

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