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A370795 Centered square numbers which are products of four distinct primes (or tetraprimes). 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
All terms are odd.
LINKS
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
KEYWORD
nonn
AUTHOR
Massimo Kofler, Mar 02 2024
STATUS
approved

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Last modified July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)