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

1, 7, 49, 2863, 14564221, 72835422814147, 49145621352814145672872849, 286372835421472135145672872835424914564914562863, 1456422149145621352814728491472135728354249145649145621352814286372835422863728354214564221

Offset

1,2

Links

John Cerkan, Table of n, a(n) for n = 1..12

Mathematica

NestList[FromDigits[Flatten[IntegerDigits/@(7*IntegerDigits[#])]]&, 1, 10] (* Harvey P. Dale, Jan 23 2015 *)

Prog

(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
(Python)
def A061585_first(n):
    an = "1"
    a061585 = []
    while n > 1:
        a061585.append(int(an))
        newan = ""
        for i in an:
            newan += str(7*int(i))
        an = newan
        n -= 1
    a061585.append(int(an))
    return a061585 # John Cerkan, May 25 2018

Crossrefs

Cf. A061581, A061582, A061583, A061584, A061586, A061587.

Sequence in context: A229041 A263247 A259990 * A202782 A067214 A069032

Adjacent sequences: A061582 A061583 A061584 * A061586 A061587 A061588

Keyword

nonn,base,easy

Author

Amarnath Murthy, May 13 2001

Extensions

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

Corrected by Harvey P. Dale, Jan 23 2015

Status

approved