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A178739 Product of the 4th power of a prime (A030514) and a different prime (p^4*q). 20
48, 80, 112, 162, 176, 208, 272, 304, 368, 405, 464, 496, 567, 592, 656, 688, 752, 848, 891, 944, 976, 1053, 1072, 1136, 1168, 1250, 1264, 1328, 1377, 1424, 1539, 1552, 1616, 1648, 1712, 1744, 1808, 1863, 1875, 2032, 2096, 2192, 2224, 2349, 2384, 2416, 2511 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A030628.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

Index to sequences related to prime signature

FORMULA

Solutions of the equation tau(n^9)=37*tau(n). - Paolo P. Lava, Mar 15 2013

a(n) ~ kn log n with k = 1/P(4) = 1/A085964 = 12.98817.... - Charles R Greathouse IV, Feb 23 2017

MAPLE

with(numtheory);

A178739:=proc(q) local n;

for n from 1 to q do if tau(n^9)=37*tau(n) then print(n); fi; od; end:

A178739(10^10);  # Paolo P. Lava, Mar 15 2013

MATHEMATICA

f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 4}; Select[Range[10000], f] (* Vladimir Joseph Stephan Orlovsky, May 03 2011 *)

max = 500000; A178739 = DeleteCases[Union[Table[Prime[p] Prime[q]^4 Boole[p != q], {p, PrimePi[max/16]}, {q, PrimePi[max/2]}]], 0]; Take[A178739, 50] (* Alonso del Arte, Aug 05 2012 *)

PROG

(PARI) list(lim)=my(v=List(), t); forprime(p=2, (lim\2)^(1/4), t=p^4; forprime(q=2, lim\t, if(p==q, next); listput(v, t*q))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 20 2011

CROSSREFS

Cf. A065036, A030514, A030628, A085986, A085987.

Sequence in context: A110229 A108608 A030628 * A261548 A065911 A260841

Adjacent sequences:  A178736 A178737 A178738 * A178740 A178741 A178742

KEYWORD

easy,nonn

AUTHOR

Will Nicholes, Jun 08 2010

STATUS

approved

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Last modified June 22 12:24 EDT 2017. Contains 288613 sequences.