A071440 Start with 1; add the digits of the previous term and the squares of the digits of the previous term.

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

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 * A371513 A280043 A309813

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