A072845 {1, 3, 7, 9} -> Mod[ {1*{1, 3, 7, 9}, 3*{1, 3, 7, 9}, 7*{1, 3, 7, 9}, 9*{1, 3, 7, 9}}, 10}.

1, 3, 7, 9, 1, 3, 7, 9, 3, 9, 1, 7, 7, 1, 9, 3, 9, 7, 3, 1, 1, 3, 7, 9, 3, 9, 1, 7, 7, 1, 9, 3, 9, 7, 3, 1, 3, 9, 1, 7, 9, 7, 3, 1, 1, 3, 7, 9, 7, 1, 9, 3, 7, 1, 9, 3, 1, 3, 7, 9, 9, 7, 3, 1, 3, 9, 1, 7, 9, 7, 3, 1, 7, 1, 9, 3, 3, 9, 1, 7, 1, 3, 7, 9, 1, 3, 7, 9, 3, 9, 1, 7, 7, 1, 9, 3, 9, 7, 3, 1, 3, 9, 1, 7, 9

Offset: 1

Author

Roger L. Bagula, Jul 24 2002

Keywords

• nonn
• uned
• less

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

Programs

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]]

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

Extensions

Edited by Robert G. Wilson v, Jul 27 2002