The On-Line Encyclopedia of Integer Sequences (OEIS)

A372296 revision #9

A372296

Taxicab numbers that are sandwiched between nonsquarefree numbers.

20683, 216125, 327763, 593047, 684019, 842751, 1845649, 2691451, 4505949, 4744376, 5004125, 5772403, 6058747, 7640128, 8029000, 8216000, 8494577, 10702783, 10765603, 10821896, 11859211, 12533824, 13731319, 14916727, 16776487, 18406603, 18617625, 20616463, 22031576, 24480125, 25937576, 27529073

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..32.

Christian Boyer, Les nombres Taxicabs, in Dossier Pour La Science, pp. 26-28, Volume 59 (Jeux math') April/June 2008 Paris.

EXAMPLE

20683 = 13 ⋅ 37 ⋅ 43 (between 20682 = 2 ⋅ 3^3 ⋅ 383 and 20684 = 2^2 ⋅ 5171).

216125 = 5^3 ⋅ 7 ⋅ 13 ⋅ 19 (between 216124 = 2^2 ⋅ 71 ⋅ 761 and 216126 = 2 ⋅ 3^2 ⋅ 12007).

327763 = 31 ⋅ 37 ⋅ 109 (between 327762 = 2 ⋅ 3^2 ⋅ 131 ⋅ 139 and 327764 = 2^2 ⋅ 67 ⋅ 1223).

MATHEMATICA

Select[Import["https://oeis.org/A001235/b001235.txt", "Table"][[;; , 2]], # < 3*10^7 && Nor @@ SquareFreeQ /@ (# + {-1, 1}) &] (* Amiram Eldar, Apr 25 2024 *)

CROSSREFS

Cf. A001235, A011541, A013929, A371602.

Sequence in context: A028519 A247926 A107263 * A237329 A292021 A183631

Adjacent sequences: A372293 A372294 A372295 * A372297 A372298 A372299

KEYWORD

nonn

AUTHOR

Massimo Kofler, Apr 25 2024

STATUS

proposed