

A298487


a(n) is the least number with persistence n as defined using A114570.


0



1, 10, 19, 43, 67, 83, 92, 293, 691, 958, 7849, 49670, 94976, 880096, 7090761, 80890670, 798992994, 9999069559, 808009099075, 8979948969844, 898989690790838
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OFFSET

0,2


COMMENTS

Repeat A114570 until one digit remains.
a(n) is the first number with persistence n in base 10.
a(n+1) <= Sum_{i=0..a(n)1} 10^i showing the sequence is infinite.
a(n) does not necessarily pass through a(n1) on the first step.


LINKS

Table of n, a(n) for n=0..20.


EXAMPLE

a(5) = 83 because:
83 > 8^2 + 3^1 = 67;
67 > 6^2 + 7^1 = 43;
43 > 4^2 + 3^1 = 19;
17 > 1^2 + 9^1 = 10;
10 > 1^2 + 0^1 = 1;
83 is the least integer to take 5 steps to get to 1 digit.


PROG

(PARI) a114570(n) = my(d=digits(n), k=#d); sum(i=1, k, d[i]^(k+1i));
p(n) = my(ip=0); while(n >= 10, n = a114570(n); ip++); ip;
a(n) = {my(k=1); while (p(k) != n, k++); k; } \\ Michel Marcus, Jan 25 2018


CROSSREFS

Cf. A114570.
Sequence in context: A127194 A083705 A245003 * A082659 A088409 A219959
Adjacent sequences: A298484 A298485 A298486 * A298488 A298489 A298490


KEYWORD

nonn,base,more


AUTHOR

John Harmon, Jan 20 2018


EXTENSIONS

a(19) from Giovanni Resta, Jan 22 2018
a(20) from Giovanni Resta, Feb 01 2018


STATUS

approved



