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A071440 Start with 1; add the digits of the previous term and the squares of the digits of the previous term. 2
1, 2, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48, 92, 96, 132, 20, 6, 42, 26, 48 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The sequence becomes periodic after ten steps: a(10) = a(2). Period length is 8, length of the preperiodic part is 2. - Other starting values except 9, 90, 900, ... result in sequences which exhibit essentially the same behavior.

LINKS

Table of n, a(n) for n=0..69.

EXAMPLE

42 -> 4 + 2 + 4^2 + 2^2 = 26, 26 -> 2 + 6 + 2^2 + 6^2 = 48, ...

PROG

(PARI) {m=70; a=1; for(j=1, m, print1(a, ", "); n=a; a=0; while(n>0, d=divrem(n, 10); n=d[1]; a=a+(1+d[2])*d[2]))}

CROSSREFS

Sequence in context: A326268 A096138 A004153 * A280043 A309813 A033936

Adjacent sequences:  A071437 A071438 A071439 * A071441 A071442 A071443

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane, Oct 23 2002

EXTENSIONS

Edited and extended by Klaus Brockhaus, Oct 24 2002

STATUS

approved

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Last modified February 23 00:28 EST 2020. Contains 332157 sequences. (Running on oeis4.)