OFFSET
1,1
LINKS
Stefano Spezia, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = (A346507(n) - 1)/10.
Conjecture: lim_{n->infinity} a(n)/a(n-1) = 1.
The conjecture is true since a(n) = (A346507(n) - 1)/10 and lim_{n->infinity} A346507(n)/A346507(n-1) = 1. - Stefano Spezia, Aug 21 2021
EXAMPLE
107 is a term because 21*51 = 1071 = 107*10 + 1.
MATHEMATICA
a={}; For[n=1, n<=350, n++, For[k=1, k<n, k++, If[Mod[10n+1, 10k+1]==0 && Mod[(10n+1)/(10k+1), 10]==1 && 10n+1>Max[10a+1], AppendTo[a, n]]]]; a
PROG
(Python)
def aupto(lim): return sorted(set(a*b//10 for a in range(11, 10*lim//11+2, 10) for b in range(a, 10*lim//a+2, 10) if a*b//10 <= lim))
print(aupto(318)) # Michael S. Branicky, Aug 21 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Stefano Spezia, Jul 21 2021
STATUS
approved