A359089 - OEIS

A359089

a(n) is the index of the smallest tetrahedral number with exactly n distinct prime factors.

1, 2, 3, 7, 18, 34, 90, 259, 988, 2583, 5795, 37960, 101268, 424268, 3344614, 17168723, 74282570, 351200178, 1082950218, 5313193819, 31439710664, 317760710839, 1782400663483

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..22.

Eric Weisstein's World of Mathematics, Distinct Prime Factors

Eric Weisstein's World of Mathematics, Tetrahedral Number

MATHEMATICA

r = -1; Reap[Do[If[# > r, r = #; Sow[n]] &[PrimeNu[n (n + 1) (n + 2)/6]], {n, 2^19}] ][[-1, -1]] (* Michael De Vlieger, Dec 19 2022 *)

PROG

(PARI) t(n) = n*(n+1)*(n+2)/6; \\ A000292

a(n) = my(k=1); while (omega(t(k)) != n, k++); k; \\ Michel Marcus, Dec 19 2022

CROSSREFS

Cf. A000292, A001221, A156329, A359017, A359090.

Sequence in context: A058334 A303090 A131093 * A343358 A002864 A005248

Adjacent sequences: A359086 A359087 A359088 * A359090 A359091 A359092

KEYWORD

nonn,more

AUTHOR

Ilya Gutkovskiy, Dec 16 2022

STATUS

approved