A354447 Taxicab numbers (sums of 2 cubes in more than 1 way) which are products of four distinct primes.

684019, 704977, 2691451, 3242197, 3375001, 4931101, 5318677, 5772403, 8872487, 10702783, 16983854, 20616463, 24897817, 41258737, 46343059, 60698521, 66469429, 69625969, 79692193, 89576767, 95731489, 96753187, 97867441, 116773741, 119793457, 126516061, 147187369

Offset

1,1

Comments

A squarefree subsequence of taxicab numbers.

Links

Table of n, a(n) for n=1..27.

Eric Weisstein's World of Mathematics, Taxicab Number

Example

684019 =  51^3 +  82^3 =  64^3 +  75^3 =  7 * 19 *  37 *  139.
8872487 =  14^3 + 207^3 = 140^3 + 183^3 = 13 * 17 *  19 * 2113.
96753187 = 147^3 + 454^3 = 283^3 + 420^3 = 19 * 37 * 229 *  601.

Mathematica

Select[Range[10^6], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} && Length @ PowersRepresentations[#, 2, 3] > 1 &] (* Amiram Eldar, May 30 2022 *)

Crossrefs

Intersection of A001235 and A046386.

Sequence in context: A236986 A258607 A081415 * A101698 A323805 A185865

Adjacent sequences: A354444 A354445 A354446 * A354448 A354449 A354450

Keyword

nonn

Author

Massimo Kofler, May 30 2022

Status

approved