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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A281920 9th power analog of Keith numbers. 1
1, 54, 71, 81, 196, 424, 451, 2394, 9057, 51737, 52141, 104439, 227914, 228088, 1019555, 1096369, 1202713, 1687563, 1954556, 3332130, 3652731, 4177592, 31669012 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Like Keith numbers but starting from n^9 digits to reach n.

Consider the digits of n^9. Take their sum and repeat the process deleting the first addend and adding the previous sum. The sequence lists the numbers that after some number of iterations reach a sum equal to n.

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

196^9 = 426878854210636742656:

4 + 2 + 6 + 8 + 7 + 8 + 8 + 5 + 4 + 2 + 1 + 0 + 6 + 3 + 6 + 7 + 4 + 2 + 6 + 5 + 6 = 100;

2 + 6 + 8 + 7 + 8 + 8 + 5 + 4 + 2 + 1 + 0 + 6 + 3 + 6 + 7 + 4 + 2 + 6 + 5 + 6 + 100 = 196.

MAPLE

with(numtheory): P:=proc(q, h, w) local a, b, k, t, v; global n; v:=array(1..h);

for n from 1 to q do b:=n^w; a:=[];

for k from 1 to ilog10(b)+1 do a:=[(b mod 10), op(a)]; b:=trunc(b/10); od;

for k from 1 to nops(a) do v[k]:=a[k]; od; b:=ilog10(n^w)+1;

t:=nops(a)+1; v[t]:=add(v[k], k=1..b); while v[t]<n do t:=t+1; v[t]:=add(v[k], k=t-b..t-1);

od; if v[t]=n then print(n); fi; od; end: P(10^6, 10000, 9);

CROSSREFS

Cf. A007629, A246544, A263534, A274769, A274770, A281915 - A281919, A281921.

Sequence in context: A025331 A025323 A157934 * A005129 A039532 A007244

Adjacent sequences:  A281917 A281918 A281919 * A281921 A281922 A281923

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Feb 02 2017

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 18 17:49 EST 2018. Contains 317323 sequences. (Running on oeis4.)