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 A001103 Numbers n such that (n / product of digits of n) is 1 or a prime. 2
 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 15, 24, 36, 115, 175, 212, 624, 735, 816, 1115, 1184, 1197, 1416, 2144, 3171, 3276, 3915, 6624, 7119, 8832, 9612, 11133, 11212, 11331, 12128, 12216, 12768, 13131, 21184, 21728, 24912, 31113, 31488, 32172, 32616, 35175 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For terms > 10 the quotient (n / product of digits of n) is prime. - David A. Corneth, Mar 30 2021 LINKS David A. Corneth, Table of n, a(n) for n = 1..12677 (first 448 terms from Klaus Brockhaus, terms <= 10^12) EXAMPLE 21728 is in the sequence as 21728/(2*1*7*2*8) = 97 which is prime. - David A. Corneth, Mar 30 2021 MAPLE P:=proc(n) local a; a:=convert(convert(n, base, 10), `*`); if a>0 then a:=n/a; if frac(a)=0 then if isprime(a) then n; fi; fi; fi; end: seq(P(i), i=1..10^5); # Paolo P. Lava, Feb 05 2018 MATHEMATICA okQ[n_] := Block[{p = Times @@ IntegerDigits[n]}, n == p || PrimeQ[n/p]]; Select[ Range[36000], okQ] PROG (MAGMA) IsA001103:=func< n | p ne 0 and n mod p eq 0 and (q eq 1 or IsPrime(q)) where q is (p eq 0 select 0 else n div p) where p is &*Intseq(n) >; [ n: n in [1..40000] | IsA001103(n) ]; // Klaus Brockhaus, Jan 24 2011 (Haskell) a001103 n = a001103_list !! (n-1) a001103_list = filter f a052382_list where    f x = m == 0 && (x' == 1 || a010051 x' == 1) where        (x', m) = divMod x \$ a007954 x -- Reinhard Zumkeller, Nov 02 2011 (PARI) is(n) = { my(vp = vecprod(digits(n))); if(vp > 0, c = n/vp; if(denominator(c) == 1, if(c == 1 || isprime(c), return(1)))); 0} \\ David A. Corneth, Mar 30 2021 CROSSREFS Cf. A007954, A066577. Cf. A052382, A010051, A007602, A188642. Sequence in context: A030721 A190296 A143288 * A265730 A304248 A147591 Adjacent sequences:  A001100 A001101 A001102 * A001104 A001105 A001106 KEYWORD nonn,base,nice AUTHOR N. J. A. Sloane, Bill Moran (moran1(AT)llnl.gov) STATUS approved

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Last modified May 14 13:50 EDT 2021. Contains 343884 sequences. (Running on oeis4.)