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A036328 Composite numbers n such that juxtaposition of prime factors of n has length 4. 1
16, 24, 36, 40, 44, 52, 54, 56, 60, 66, 68, 76, 78, 81, 84, 90, 92, 99, 100, 102, 110, 114, 116, 117, 121, 124, 126, 130, 135, 138, 140, 143, 148, 150, 153, 154, 164, 165, 169, 170, 171, 172, 174, 182, 186, 187, 188, 189, 190, 195, 196, 202, 206, 207, 209, 210 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The last term of this sequence is a(1048)=9409.

Prime factors are taken with multiplicity. - Harvey P. Dale, Dec 05 2015

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..1048 (full sequence)

MAPLE

isA036328 := proc(n) local d: d:=ifactors(n)[2]: return `if`(not isprime(n) and add(length(d[j][1])*d[j][2], j=1..nops(d))=4, n, NULL): end: l:=[seq(isA036328(n), n=2..9999)]; # Nathaniel Johnston, Jun 22 2011

MATHEMATICA

jpf4Q[n_]:=Length[Flatten[IntegerDigits/@Table[#[[1]], {#[[2]]}]&/@FactorInteger[n]]]==4; Select[Range[300], jpf4Q] (* Harvey P. Dale, Dec 05 2015 *)

CROSSREFS

Cf. A036326-A036334.

Sequence in context: A163284 A100316 A206260 * A067028 A110893 A014613

Adjacent sequences:  A036325 A036326 A036327 * A036329 A036330 A036331

KEYWORD

nonn,base,fini,full,easy

AUTHOR

Patrick De Geest, Dec 15 1998

STATUS

approved

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Last modified January 21 18:52 EST 2021. Contains 340352 sequences. (Running on oeis4.)