A354086 11-gonal numbers which are products of four distinct primes.

4785, 8170, 11526, 14421, 27105, 30710, 38595, 59110, 60146, 77946, 94105, 107570, 118990, 120458, 121935, 132526, 140361, 141955, 156706, 158390, 161785, 181101, 199606, 203415, 213095, 215058, 217030, 221001, 243485, 249806, 267058, 287155, 298635, 303290

Offset: 1

Author

Massimo Kofler, Jun 08 2022

Keywords

• nonn

Comments

A squarefree subsequence of 11-gonal numbers, i.e., numbers of the form k*(9*k-7)/2.

Examples

			4785 = 33*(9*33-7)/2 = 3*5*11*29.
30710 = 83*(9*83-7)/2 = 2*5*37*83.
140361 = 177*(9*177-7)/2 = 3*13*59*61.
303290 = 260*(9*260-7)/2 = 2*5*13*2333.
		

Crossrefs

Intersection of A051682 and A046386.

Programs

Maple

q:= n-> is(map(x-> x[2], ifactors(n)[2])=[1$4]):
select(q, [n*(9*n-7)/2$n=1..300])[];  # Alois P. Heinz, Jun 15 2022

Mathematica

Select[Table[n*(9*n - 7)/2, {n, 1, 300}], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} &] (* Amiram Eldar, Jun 08 2022 *)