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A354976
Tetrahedral numbers which are products of five distinct primes.
0
7770, 14190, 98770, 121485, 129766, 273819, 383306, 457310, 632710, 735130, 848046, 971970, 1072445, 1456935, 1543465, 2027795, 2135445, 2190670, 2731135, 3136805, 3817670, 4775385, 4869634, 5159805, 5564321, 5989445, 6099006, 6209895, 8579746, 9145270, 9735114, 9886435
OFFSET
1,1
COMMENTS
A squarefree subsequence of tetrahedral numbers.
EXAMPLE
7770 = 35*36*37/6 = 2*3*5*7*37
14190 = 43*44*45/6 = 2*3*5*11*43
98770 = 83*84*85/6 = 2*5*7*17*83
121485 = 89*90*91/6 = 3*5*7*13*89
MAPLE
q:= n-> is(map(x-> x[2], ifactors(n)[2])=[1$5]):
select(q, [n*(n+1)*(n+2)/6$n=1..500])[]; # Alois P. Heinz, Jun 15 2022
MATHEMATICA
Select[Table[n*(n+1)*(n+2)/6, {n, 1, 400}], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1, 1} &] (* Amiram Eldar, Jun 15 2022 *)
CROSSREFS
Intersection of A000292 and A046387.
Subsequence of A070755.
Sequence in context: A031646 A252556 A028538 * A123990 A176375 A210116
KEYWORD
nonn
AUTHOR
Massimo Kofler, Jun 15 2022
STATUS
approved