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A063543
a(n) = n - product of nonzero digits of n.
6
0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 18, 19, 18, 17, 16, 15, 14, 13, 12, 11, 27, 28, 26, 24, 22, 20, 18, 16, 14, 12, 36, 37, 34, 31, 28, 25, 22, 19, 16, 13, 45, 46, 42, 38, 34, 30, 26, 22, 18, 14, 54, 55, 50, 45, 40, 35, 30, 25, 20, 15, 63, 64, 58
OFFSET
1,10
COMMENTS
The graph somewhat resembles wisteria flowers.
LINKS
N. J. A. Sloane and Brady Haran, Amazing Graphs II (including Star Wars), Numberphile video (2019).
EXAMPLE
a(20) = 20 - 2 = 18.
MAPLE
a:= n-> n-mul(i, i=subs(0=1, convert(n, base, 10))):
seq(a(n), n=1..80); # Alois P. Heinz, Aug 18 2019
MATHEMATICA
Table[n - Times@@DeleteCases[IntegerDigits[n], 0], {n, 70}] (* Alonso del Arte, Dec 15 2013 *)
PROG
(PARI) ProdNzD(x)= { local(d, p); p=1; while (x>9, d=x-10*(x\10); if (d, p*=d); x\=10); return(p*x) }
{ for (n=1, 2000, write("b063543.txt", n, " ", n - ProdNzD(n)) ) } \\ Harry J. Smith, Aug 25 2009
(PARI) a(n) = my(d=select(x->(x!=0), digits(n))); n - vecprod(d); \\ Michel Marcus, Jan 13 2020
(Python)
def a(n):
digits = map(int, str(n))
product = 1
for d in digits:
if d != 0:
product *= d
return n - product
[a(n) for n in range(20)]
# Elisabeth Zemack, Sep 16 2019; corrected by Fabio Somenzi, Jan 13 2020
(Magma) [n - &*[a: k in [1..#Intseq(n)] | a ne 0 where a is Intseq(n)[k]]: n in [1..100]]; // Marius A. Burtea, Sep 16 2019
CROSSREFS
Cf. A063114.
Sequence in context: A158001 A157763 A010735 * A096166 A240919 A078548
KEYWORD
nonn,base,easy,look
AUTHOR
N. J. A. Sloane, Aug 14 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), Aug 14 2001
STATUS
approved