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

101556, 121968, 124012, 133875, 144648, 172900, 185472, 226800, 352170, 433755, 2096640, 3779136, 4264416, 5166504, 5333680, 5448960, 5651919, 5894784, 5955264, 5983936, 6003088, 6174630, 6197724, 6324318, 6351840, 6429600, 6494400, 6514060, 6794424, 6874560, 7064496

Offset

1,1

Comments

Subsequence of A072443.

Links

David A. Corneth, Table of n, a(n) for n = 1..10408 (terms <= 2*10^10)

Example

101556 = 156*651 = 273*372; 2096640 = 1092*1920 = 1365*1536.

Prog

(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)))))))}

Crossrefs

Cf. A000037, A072443.

Sequence in context: A229684 A187642 A023077 * A218170 A153050 A203592

Adjacent sequences: A077757 A077758 A077759 * A077761 A077762 A077763

Keyword

nonn,base

Author

Klaus Brockhaus, Nov 14 2002

Extensions

Offset changed to 1 by and more terms from David A. Corneth, Sep 08 2024

Status

approved