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A095990 Numbers with ordered prime signature (1,2). 7
18, 50, 75, 98, 147, 242, 245, 338, 363, 507, 578, 605, 722, 845, 847, 867, 1058, 1083, 1183, 1445, 1587, 1682, 1805, 1859, 1922, 2023, 2523, 2527, 2645, 2738, 2883, 3179, 3362, 3698, 3703, 3757, 3971, 4107, 4205, 4418, 4693, 4805, 5043, 5547, 5618, 5819 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers of the form p*q^2 where p and q are primes with p < q.

A054753 contains natural numbers with ordered prime signatures (2,1) and (1,2).

LINKS

Enrique PĂ©rez Herrero, Table of n, a(n) for n = 1..3000

OEIS Wiki, Ordered prime signatures

EXAMPLE

18 = 2*3*3, 50 = 2*5*5, 75 = 3*5*5, 98 = 2*7*7, 147 = 3*7*7, ...

MATHEMATICA

Take[ Sort[ Flatten[ Table[ Prime[p]*Prime[q]^2, {q, 2, 16}, {p, q - 1}]]], 46] (* Robert G. Wilson v, Jul 23 2004 *)

PROG

(PARI) list(lim)=my(v=List()); forprime(q=3, sqrtint(lim\2), forprime(p=2, min(lim\q^2, q-1), listput(v, p*q^2))); Set(v) \\ Charles R Greathouse IV, Feb 26 2014

CROSSREFS

Subsequence of A071365.

Cf. A054753, A095904, A096156.

Sequence in context: A093617 A089219 A102835 * A102836 A217750 A180292

Adjacent sequences:  A095987 A095988 A095989 * A095991 A095992 A095993

KEYWORD

easy,nonn

AUTHOR

Alford Arnold, Jul 18 2004

EXTENSIONS

Edited and extended by Robert G. Wilson v, Jul 23 2004

STATUS

approved

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Last modified March 7 09:34 EST 2021. Contains 341869 sequences. (Running on oeis4.)