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 A356355 9-gonal numbers which are products of five distinct primes. 0
 24486, 71214, 90321, 116754, 123234, 156774, 181374, 265926, 287574, 445179, 450186, 483414, 488631, 595959, 688866, 698214, 781869, 791826, 845994, 912646, 937839, 970734, 1030614, 1042041, 1100121, 1266909, 1463514, 1659801, 2014386, 2041026, 2171334, 2187906 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A squarefree subsequence of 9-gonal numbers a(n) = n*(7*n-5)/2. LINKS Table of n, a(n) for n=1..32. EXAMPLE 24486 = 2*3*7*11*53 = 84*(7*84-5)/2. 445179 = 3*7*17*29*43 = 357*(7*357-5)/2. 781869 = 3*11*19*29*43 = 473*(7*473-5)/2. 1030614 = 2*3*13*73*181 = 543*(7*543-5)/2. MATHEMATICA Select[Table[n*(7*n - 5)/2, {n, 1, 1000}], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1, 1} &] (* Amiram Eldar, Oct 15 2022 *) PROG (PARI) select(x->omega(x)==5&&bigomega(x)==5, vector(800, k, k*(7*k-5)/2)) \\ Michel Marcus, Nov 26 2022 CROSSREFS Intersection of A001106 and A046387. Sequence in context: A083622 A237207 A224423 * A258441 A244150 A229798 Adjacent sequences: A356352 A356353 A356354 * A356356 A356357 A356358 KEYWORD nonn AUTHOR Massimo Kofler, Oct 15 2022 STATUS approved

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Last modified June 15 22:50 EDT 2024. Contains 373412 sequences. (Running on oeis4.)