login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128212 a(n) = Sum_digits(p), where p is the product of the digits of n. 2
1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 2, 4, 6, 8, 1, 3, 5, 7, 9, 0, 3, 6, 9, 3, 6, 9, 3, 6, 9, 0, 4, 8, 3, 7, 2, 6, 10, 5, 9, 0, 5, 1, 6, 2, 7, 3, 8, 4, 9, 0, 6, 3, 9, 6, 3, 9, 6, 12, 9, 0, 7, 5, 3, 10, 8, 6, 13, 11, 9, 0, 8, 7, 6, 5, 4, 12, 11, 10, 9, 0, 9, 9, 9, 9, 9, 9, 9, 9, 9, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence grows very slowly. For n <= 10000 the maximal value is 27.

LINKS

Marius A. Burtea, Table of n, a(n) for n = 1..6000

FORMULA

a(n) = A007954(A007953(n)). - Michel Marcus, Jun 07 2019

EXAMPLE

a(73) = 3 because 7*3 = 21 and 2+1 = 3.

MAPLE

P:=proc(n) local i, k, w; for i from 1 by 1 to n do w:=1; k:=i; while k>0 do w:=w*(k-(trunc(k/10)*10)); k:=trunc(k/10); od; k:=w; w:=0; while k>0 do w:=w+k-(trunc(k/10)*10); k:=trunc(k/10); od; print(w); od; end: P(100);

MATHEMATICA

Table[Total[IntegerDigits[Times@@IntegerDigits[n]]], {n, 100}] (* Harvey P. Dale, Feb 08 2013 *)

PROG

(MAGMA) [&+Intseq((&*(Intseq(n)))):n in [1..100]]; // Marius A. Burtea, Jun 06 2019

(PARI) a(n) = sumdigits(vecprod(digits(n))); \\ Michel Marcus, Jun 07 2019

CROSSREFS

Cf. A007953, A007954.

Sequence in context: A062078 A031347 A087471 * A187844 A007954 A079475

Adjacent sequences:  A128209 A128210 A128211 * A128213 A128214 A128215

KEYWORD

easy,nonn,base

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, May 03 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 06:19 EDT 2019. Contains 328048 sequences. (Running on oeis4.)