|
%I #15 Dec 12 2020 21:50:13
%S 1,1,2,6,24,1020,60120,4207140,32160568320,2718954045547227180,
%T 207010809050400405050407020207010800,
%U 22077011088099055044004405505504407702202207701108800,24240848401212096960108108060600484800484806060060600484808484024240242408484012120969600
%N a(0) = 1, a(n) = number obtained by multiplying each digit of a(n-1) by n. May be called digitfactorial of n.
%H Alois P. Heinz, <a href="/A089718/b089718.txt">Table of n, a(n) for n = 0..15</a>
%p str10:=proc(n) if n<>0 then RETURN(convert(n,base,10)) else RETURN([0]) fi end:ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1),j=1..nops(s))): end: ap:=1: for n from 1 to 12 do m:=ds([seq(op(str10(i*n)),i=str10(ap))]): printf("%d, ",m):ap:=m od: # C. Ronaldo
%p # second Maple program:
%p a:= proc(n) option remember; `if`(n=0, 1, (l-> parse(cat(seq(
%p l[-i]*n, i=1..nops(l)))))(convert(a(n-1), base, 10)))
%p end:
%p seq(a(n), n=0..12); # _Alois P. Heinz_, Dec 12 2020
%t nxt[{n_,a_}]:={n+1,FromDigits[Flatten[IntegerDigits/@((n+1)*IntegerDigits[ a])]]}; Transpose[NestList[nxt,{1,1},10]][[2]] (* _Harvey P. Dale_, Mar 26 2015 *)
%Y Cf. A000142, A110728.
%K base,easy,nonn
%O 0,3
%A _Amarnath Murthy_, Nov 18 2003
%E More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
%E a(0)=1 prepended by _Alois P. Heinz_, Dec 12 2020
|
