OFFSET

1,2

COMMENTS

Let S(1) = {1, 3, 7, 9}, S(n) be obtained from S(n-1) via 1 -> {1, 3, 7, 9}, 3 -> {3, 9, 1, 7}, 7 -> {7, 1, 9, 3}, 9 -> {9, 7, 3, 1}, then this sequence is the concatenation of S(1), S(2), ... - Jianing Song, Dec 24 2022

MAPLE

S[1]:= [1, 3, 7, 9]:

R:= [1=(1, 3, 7, 9), 3 = (3, 9, 1, 7), 7 = (7, 1, 9, 3), 9 = (9, 7, 3, 1)]:

for i from 1 to 4 do S[i+1]:= subs(R, S[i]) od:

seq(op(S[i]), i=1..5); # Robert Israel, Dec 25 2022

MATHEMATICA

ar={1, 3, 7, 9};

f[x_]=Mod[ar*x, 10];

br=Flatten[ NestList[f, ar, 3]]

PROG

(PARI) lista(nn) = {my(m = [1, 3, 7, 9], v = m); for (i=1, nn, my(w = []); for (j=1, 4, for (k=1, #v, w = concat(w, m[j]*v[k] % 10); ); ); v = w; ); w; }

lista(3) \\ Michel Marcus, Jul 01 2019

CROSSREFS

KEYWORD

nonn,uned,less

AUTHOR

Roger L. Bagula, Jul 24 2002

EXTENSIONS

Edited by Robert G. Wilson v, Jul 27 2002

STATUS

approved