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A243218
Number of n-digit integers x such that x + A007954(x) has n digits, where A007954(x) is the product of decimal digits of x.
2
5, 63, 756, 8268, 86225, 880519, 8898517, 89471520, 897248572, 8985712192, 89925825853, 899614672173, 8997997446679, 89989593213308, 899945924502919, 8999718992342921, 89998539650321017, 899992410699128981, 8999960560129165187, 89999795045731606967
OFFSET
1,1
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..35
EXAMPLE
For n=1, the five 1-digit integers 0,1,2,3,4 satisfy the condition, with results being respectively 0,2,4,6 and 8, hence a(1)=5.
PROG
(PARI) DP(n)= my(d = digits(n)); prod(i=1, #d, d[i]);
a(n) = {nb = 0; if (n==1, istart = 0, istart = 10^(n-1)); for (i=istart, 10^n-1, if (i + DP(i) < 10^n, nb++); ); nb; }
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Marcus, Jun 01 2014
EXTENSIONS
a(9)-a(17) from Hiroaki Yamanouchi, Sep 29 2014
a(18)-a(20) from Hiroaki Yamanouchi, Jan 08 2016
STATUS
approved