OFFSET

1,1

COMMENTS

a(9) <= 22963573117 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 09 2007

a(11) <= 15084115509707 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 06 2007

a(29) <= 112237795073 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 09 2007

a(39) <= 3753219157 from Joe K. Crump (joecr(AT)carolina.rr.com), Feb 10 2007

LINKS

MATHEMATICA

t = Table[0, {10000} ]; k = 1; While[ k < 4000000000, a = PowerMod[10, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t

PROG

(Python)

def a(n):

k = 1

while 10**k % k != n: k += 1

return k

print([a(n) for n in range(1, 9)]) # Michael S. Branicky, Mar 14 2021

CROSSREFS

KEYWORD

hard,nonn

AUTHOR

Alexander Adamchuk, Jan 30 2007

EXTENSIONS

Crump's values for a(9), a(11), a(39) confirmed, a(29) = 10191082613 = 16763 * 607951 by Hagen von Eitzen, Jul 29 2009

STATUS

approved