A370795 Centered square numbers which are products of four distinct primes (or tetraprimes).

99905, 107185, 242905, 350285, 363805, 372385, 433381, 569245, 590785, 630565, 692665, 752765, 907205, 942565, 1026745, 1076045, 1090765, 1105585, 1227745, 1275205, 1333345, 1467185, 1526005, 1647113, 1661665, 1761565, 1810705, 1911013, 2026085, 2317705, 2395861, 2470865

Offset

1,1

Comments

All terms are odd.

Links

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

Formula

a(n) == 1 (mod 4).

Example

99905 = 5 * 13 * 29 * 53 = (2 * 223 * 224) + 1.
107185 = 5 * 13 * 17 * 97 = (2 * 231 * 232) + 1.
242905 = 5 * 13 * 37 * 101 = (2 * 348 * 349) + 1

Mathematica

Select[Table[2*n*(n + 1) + 1, {n, 0, 1200}], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} &] (* Amiram Eldar, Mar 02 2024 *)

Crossrefs

Intersection of A046386 and A001844.

Sequence in context: A268417 A232188 A032428 * A204523 A182698 A033427

Adjacent sequences: A370792 A370793 A370794 * A370796 A370797 A370798

Keyword

nonn

Author

Massimo Kofler, Mar 02 2024

Status

approved