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A258885 Primitive weird numbers (A002975) having 6 distinct prime factors. 12
1550860550, 44257207676, 66072609790 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(4) <= 5976833582079328 = 2^5*181*197*353*431*34429 and a(5) <= 48083019473926272314825065088 = 2^7*257*97213*97973*100957*1520132521 that is certainly in this sequence. - Giuseppe Melfi, Oct 26 2015

a(4) <= 125258675788784 = 2^4 * 47 * 149 * 353 * 1307 * 2423. - M. F. Hasler, Jul 12 2016

LINKS

Table of n, a(n) for n=1..3.

G. Amato, M. Hasler, G. Melfi and M. Parton, Primitive weird numbers having more than three distinct prime factors, Riv. Mat. Univ. Parma, Vol. 7, No. 1 (2016) 153-163.

G. Melfi, On the conditional infiniteness of primitive weird numbers, Journal of Number Theory, 147 (2015) 508-514; Lemma 2.

EXAMPLE

a(1) = 1550860550 = 2 * 5^2 * 29 * 37 * 137 * 211 = A273815(1). (Abundance = 20)

a(2) = 44257207676 = 2^2 * 11 * 37 * 59 * 523 * 881. (Abundance = 8, cf. A088833)

a(3) = 66072609790 = 2 * 5 * 11 * 127^2 * 167 * 223 = A273815(3). (Abundance = 4, cf. A088832)

MATHEMATICA

(* copy the terms from A002975, assign them to 'lst' and then *)

Select[ lst, PrimeNu@# == 6 &]

PROG

(PARI) select(w->omega(w)==6, A002975) \\ Assuming that A002975 is defined as set or vector. - _M. F. Hasler, Jul 12 2016_

CROSSREFS

Cf. A002975, A258401, A258882, A258883, A258884.

Sequence in context: A206045 A276820 A273815 * A216905 A166383 A227444

Adjacent sequences:  A258882 A258883 A258884 * A258886 A258887 A258888

KEYWORD

nonn,bref,hard,more

AUTHOR

Douglas E. Iannucci and Robert G. Wilson v, Jun 14 2015

EXTENSIONS

One more term added and definition corrected by Giuseppe Melfi, Nov 02 2015

STATUS

approved

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Last modified June 24 18:28 EDT 2021. Contains 345419 sequences. (Running on oeis4.)