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A263479 Total number of n-digit positive integers with multiplicative digital root value 5. 7
1, 6, 33, 132, 435, 1466, 5341, 18656, 58029, 159430, 392601, 882036, 1836159, 3586506, 6638885, 11738656, 19952441, 32768742, 52220113, 81029700, 122785131, 182142906, 265066605, 379102400, 533695525, 740551526, 1014046281, 1371688948, 1834642167, 2428304010 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

First differences of A263473.

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 1..50

FORMULA

A263476(n) + A000012(n) + A263477(n) + A000027(n) + A263478(n) + a(n) + A263480(n) + A000027(n) + A263481(n) + A000217(n) = A052268(n).

MATHEMATICA

Last /@ Tally@ IntegerLength@ Select[Range@ 1000000, FixedPoint[Times @@ IntegerDigits@ # &, #] == 5 &] (* Michael De Vlieger, Oct 21 2015 *)

PROG

(PARI) t(k) = {while(k>9, k=prod(i=1, #k=digits(k), k[i])); k}

a(n) = sum(i=10^(n-1), 10^n - 1, if(t(i) == 5, 1, 0)); \\ Altug Alkan, Oct 19 2015

CROSSREFS

Cf. A031347, A034052, A263473.

Sequence in context: A063267 A082106 A297392 * A073375 A089097 A120009

Adjacent sequences:  A263476 A263477 A263478 * A263480 A263481 A263482

KEYWORD

nonn,base

AUTHOR

Martin Renner, Oct 19 2015

EXTENSIONS

a(9)-a(30) from Hiroaki Yamanouchi, Oct 25 2015

STATUS

approved

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Last modified April 22 08:25 EDT 2019. Contains 322329 sequences. (Running on oeis4.)