A083408 Squares which can be expressed as the product of a number and its reversal in at least two different ways.

63504, 435600, 6350400, 7683984, 16240900, 25401600, 43560000, 66585600, 420332004, 558471424, 635040000, 647804304, 726949444, 768398400, 782432784, 1067328900, 1624090000, 1897473600, 2341011456, 2540160000, 4356000000, 6658560000, 42033200400, 50860172484, 52587662400

Offset

1,1

Comments

Union of A083406 and A083407. - Lekraj Beedassy, Apr 23 2006

References

S. S. Gupta, EPRNs, Science Today, Feb. 1987, India.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..2498 (n = 1..76 from Hans Havermann, n = 77..241 from David A. Corneth)

David A. Corneth, Examples of factorizations of terms as described in Name.

Shyam Sunder Gupta, EPRN Numbers.

Example

63504 = 252 * 252 = 144 * 441,
1239016098321 = 1113111 * 1113111 = 1022121 * 1212201, etc.
635040000 = 144 * 4410000 = 252 * 2520000 = 441 * 1440000. - David A. Corneth, Mar 22 2019

Prog

(PARI) is(n) = {if(!issquare(n), return(0)); my(d = divisors(n), t = 0); forstep(i = #d, #d \ 2 + 1, -1, revd = fromdigits(Vecrev(digits(d[i]))); if(revd * d[i] == n, t++; if(t >= 2, return(1)); ) ); 0 } \\ David A. Corneth, Mar 21 2019

Crossrefs

Cf. A062917, A066531, A083406 (even), A083407 (odd), A070760, A117281 (palindromic square roots), A206642 (non-palindromic square roots), A325150 (products in exactly two different ways), A307019 (products in exactly three different ways).

Sequence in context: A117282 A076750 A083406 * A325150 A072693 A119276

Adjacent sequences: A083405 A083406 A083407 * A083409 A083410 A083411

Keyword

nonn,base

Author

Shyam Sunder Gupta, Jun 07 2003

Extensions

Corrected and extended by Hans Havermann, Feb 11 2012

a(21)-a(25) from David A. Corneth, Mar 21 2019

Definition corrected by N. J. A. Sloane, Aug 01 2019

Status

approved