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.

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

Cf. A007954, A230099, A242945, A243219.

Sequence in context: A063079 A362786 A222376 * A112788 A361406 A355411

Adjacent sequences: A243215 A243216 A243217 * A243219 A243220 A243221

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