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A072443 Nonsquares which are the product of two numbers with the same digits (leading zeros are forbidden). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

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

LINKS

Table of n, a(n) for n=1..41.

EXAMPLE

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

PROG

(PARI) {for(n=100, 15000, k=floor(log(n)/log(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]))); b=matsize(v)[2]; if(b>1, 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))))))}

CROSSREFS

A076750 and A077760 are subsequences.

Sequence in context: A066695 A104396 A207373 * A129623 A062904 A032800

Adjacent sequences:  A072440 A072441 A072442 * A072444 A072445 A072446

KEYWORD

base,nonn

AUTHOR

N. J. A. Sloane, Nov 11 2002

EXTENSIONS

Extended by Klaus Brockhaus, Nov 12 2002

STATUS

approved

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Last modified November 24 20:34 EST 2020. Contains 338616 sequences. (Running on oeis4.)