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A061585 a(1) = 1, a(n)= number obtained by replacing each digit of a(n-1) with seven times its value.

%I A061585 #17 Oct 27 2023 22:05:37
%S A061585 1,7,49,2863,14564221,72835422814147,49145621352814145672872849,
%T A061585 286372835421472135145672872835424914564914562863,
%U A061585 1456422149145621352814728491472135728354249145649145621352814286372835422863728354214564221
%N A061585 a(1) = 1, a(n)= number obtained by replacing each digit of a(n-1) with seven times its value.
%H A061585 John Cerkan, <a href="/A061585/b061585.txt">Table of n, a(n) for n = 1..12</a>
%t A061585 NestList[FromDigits[Flatten[IntegerDigits/@(7*IntegerDigits[#])]]&,1,10] (* _Harvey P. Dale_, Jan 23 2015 *)
%o A061585 (PARI) A061585(n=2,a=1,m=7)={while(n--,a=eval(concat(apply(t->Str(t),digits(a)*m))));a} \\ If only the 2nd argument is given, then the operation is applied once to that argument. - _M. F. Hasler_, Jun 24 2016
%o A061585 (Python)
%o A061585 def A061585_first(n):
%o A061585     an = "1"
%o A061585     a061585 = []
%o A061585     while n > 1:
%o A061585         a061585.append(int(an))
%o A061585         newan = ""
%o A061585         for i in an:
%o A061585             newan += str(7*int(i))
%o A061585         an = newan
%o A061585         n -= 1
%o A061585     a061585.append(int(an))
%o A061585     return a061585 # _John Cerkan_, May 25 2018
%Y A061585 Cf. A061581, A061582, A061583, A061584, A061586, A061587.
%K A061585 nonn,base,easy
%O A061585 1,2
%A A061585 _Amarnath Murthy_, May 13 2001
%E A061585 More terms from Larry Reeves (larryr(AT)acm.org) and _Asher Auel_, May 15 2001
%E A061585 Corrected by _Harvey P. Dale_, Jan 23 2015