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A105997 Semiprime function n -> A001358(n) applied three times to n. 5
26, 39, 74, 77, 118, 119, 178, 194, 219, 235, 299, 301, 329, 377, 381, 454, 471, 502, 535, 565, 566, 634, 679, 703, 721, 779, 842, 886, 893, 914, 973, 995, 998, 1006, 1126, 1174, 1227, 1282, 1294, 1317, 1337, 1343, 1389, 1418, 1457, 1563, 1577, 1623, 1642 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..49.

FORMULA

a(n) = A001358(A001358(A001358(n))).

EXAMPLE

a(1) = semiprime(semiprime(semiprime(1))) = semiprime(semiprime(4)) = semiprime(10) = 26.

MATHEMATICA

f[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[ n]]; t = Select[ Range[ 1700], f[ # ] == 2 &]; Table[ Nest[ t[[ # ]] &, n, 3], {n, 50}] (* Robert G. Wilson v, Apr 30 2005 *)

CROSSREFS

Cf. A001358, A007097, A091022, A105998, A105999.

Sequence in context: A043927 A330701 A050702 * A075288 A320255 A125218

Adjacent sequences:  A105994 A105995 A105996 * A105998 A105999 A106000

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Apr 29 2005

EXTENSIONS

Corrected and extended by Robert G. Wilson v, Apr 30 2005

STATUS

approved

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Last modified January 27 14:39 EST 2020. Contains 331295 sequences. (Running on oeis4.)