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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 (list; graph; refs; listen; history; text; internal format)
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(n-1) 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+1-i));

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

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Last modified December 5 00:21 EST 2021. Contains 349530 sequences. (Running on oeis4.)