

A036325


Composite numbers n such that digits of prime factors of n are either 8 or 9.


26



7921, 704969, 800911, 8001011, 8009021, 8802011, 8810911, 8899021, 62742241, 71281079, 79120021, 80001121, 80982001, 88109911, 88910021, 712089979, 712802869, 783378979, 784171079, 791120021, 791200121, 792012869, 800020021, 800109911, 800901121, 800991011, 809001101, 809811011, 880111121
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OFFSET

1,1


COMMENTS

All terms are a product of at least two terms of A020472.  David A. Corneth, Apr 30 2018


LINKS

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 5375 terms from Robert Israel)
Index entries for sequences related to prime factors


EXAMPLE

7921 is in the sequence because it's composite and its distinct prime factors are 89, only having digits 8 or 9.  David A. Corneth, Apr 30 2018


MAPLE

N:= 9: # to get all terms of <= N digits
R:= 10^N: G:= {9}: S:= {1}:
for n from 1 to N1 do
G:= map(t > (t+8*10^n, t+9*10^n), G);
newprimes:= select(isprime, G);
for p in newprimes do
S:= map(s > seq(s*p^i, i=0..floor(log[p](R/s))), S)
od
od:
sort(convert(remove(isprime, S minus {1}), list)); # Robert Israel, Apr 30 2018


CROSSREFS

Cf. A020472, A036302A036324.
Sequence in context: A121236 A233976 A001228 * A031587 A031767 A250629
Adjacent sequences: A036322 A036323 A036324 * A036326 A036327 A036328


KEYWORD

nonn,easy,base


AUTHOR

Patrick De Geest, Dec 15 1998


EXTENSIONS

More terms from Robert Israel, Apr 29 2018


STATUS

approved



