A030631 -id:A030631 - cp's OEIS frontend

A381316 Numbers whose powerful part (A057521) is a power of a prime with an exponent >= 3 (A246549).

8, 16, 24, 27, 32, 40, 48, 54, 56, 64, 80, 81, 88, 96, 104, 112, 120, 125, 128, 135, 136, 152, 160, 162, 168, 176, 184, 189, 192, 208, 224, 232, 240, 243, 248, 250, 256, 264, 270, 272, 280, 296, 297, 304, 312, 320, 328, 336, 343, 344, 351, 352, 368, 375, 376, 378

Offset: 1

Amiram Eldar, Feb 19 2025

First differs from A344653 and A345193 at n = 17: a(17) = 120 is not a term of these sequences.
Numbers whose prime signature (A118914) is of the form {1, 1, ..., m} with m >= 3, i.e., any number (including zero) of 1's and then a single number >= 3.
The asymptotic density of this sequence is (1/zeta(2)) * Sum_{p prime} 1/(p*(p^2-1)) = A369632 / A013661 = 0.13463358553764438661... .

Amiram Eldar, Table of n, a(n) for n = 1..10000

Complement of A060687 within A190641.
Cf. A013661, A057521, A246549, A369632.
Cf. A344653, A345193.
Subsequences: A030078, A030514, A030516, A030629, A030631, A050997, A056824, A065036, A079395, A092759, A138031, A178739, A178740, A179644, A179645, A179664, A179665, A179667, A179668, A179670, A179672, A179692, A179693, A179696, A179704, A179747, A189975, A189984, A189987, A190110, A190292, A190378, A190383, A190388, A190473, A381312.

q[n_] := Module[{e = ReverseSort[FactorInteger[n][[;; , 2]]]}, e[[1]] > 2 && (Length[e] == 1 || e[[2]] == 1)]; Select[Range[1000], q]

isok(k) = if(k == 1, 0, my(e = vecsort(factor(k)[, 2], , 4)); e[1] > 2 && (#e == 1 || e[2] == 1));

A280350 Numbers with 97 divisors.

Original entry on oeis.org

79228162514264337593543950336, 6362685441135942358474828762538534230890216321, 12621774483536188886587657044524579674771302961744368076324462890625, 1347137238494276547832006567721872890819326613454654477690085519113574118965817601, 9412343651268540526001186511911506574868063110469548823950876000379062365652829504091329792873336961

Offset: 1

Omar E. Pol, Jan 02 2017

Also, 96th powers of primes.

More generally, the n-th number with p divisors is equal to the n-th prime raised to power p-1, where p is prime. In this case, p = 97.

			a(1) = 2^96, a(2) = 3^96, a(3) = 5^96, a(4) = 7^96, a(5) = 11^96.

OEIS Wiki, Index entries for number of divisors

Cf. A000005, A000040, A001248, A030514, A030516, A030629, A030631, A030635, A030637, A137486, A137492, A139571, A139572, A139573, A139574, A139575, A173533, A183062, A183085, A280298, A280299, A280301, A280346, A280347, A280349, A261700.

[NthPrime(n)^96: n in [1..5]]; // Vincenzo Librandi, Jan 06 2017

With[{p = 25}, Table[Prime[n]^(Prime[p] - 1), {n, 5}]] (* Michael De Vlieger, Jan 02 2017 *)

PARI
```
a(n)=prime(n)^96
```

a(n) = A000040(n)^(97-1) = A000040(n)^96.

A000005(a(n)) = 97.

cp's OEIS Frontend

A381316 Numbers whose powerful part (A057521) is a power of a prime with an exponent >= 3 (A246549).

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