A061583 a(1) = 1, a(n) is the number obtained by replacing each digit of a(n-1) with five times its value.

1, 5, 25, 1025, 501025, 250501025, 10250250501025, 501025010250250501025, 2505010250501025010250250501025, 1025025050102502505010250501025010250250501025

Offset: 1

Author

Amarnath Murthy, May 13 2001

Keywords

• nonn
• base
• easy

Comments

Number of digits of each term is the sequence A038718. - Dmitry Kamenetsky, Jan 17 2009

Links

• John Cerkan, Table of n, a(n) for n = 1..17

Crossrefs

Cf. A061581, A061582, A061584, A061585, A061586, A061587.

Programs

Maple

a:= proc(n) option remember; `if`(n=1, 1, (s-> parse(cat(
      seq(parse(s[i])*5, i=1..length(s)))))(""||(a(n-1))))
    end:
seq(a(n), n=1..10);  # Alois P. Heinz, May 25 2018

Mathematica

NestList[FromDigits[Flatten[IntegerDigits/@(5*IntegerDigits[#])]]&,1,10] (* Harvey P. Dale, Dec 31 2013 *)

Python

def A061583_first(n):
    an = "1"
    a061583 = []
    while n > 1:
        a061583.append(int(an))
        newan = ""
        for i in an:
            newan += str(5*int(i))
        an = newan
        n -= 1
    a061583.append(int(an))
    return a061583 # John Cerkan, May 25 2018

Extensions

More terms from Larry Reeves (larryr(AT)acm.org) and Asher Auel, May 15 2001