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A116327
k times k+8 gives the concatenation of two numbers m and m+5.
5
79, 35475530, 41357883, 58642110, 64524463, 3317813164402425001808, 3762581663871761671881, 4019782237714250566387, 4464550737183587236460, 5535449262816412763533, 5980217762285749433606, 6237418336128238328112
OFFSET
1,1
EXAMPLE
64524463 * 64524471 = 41634068//41634073, where // denotes concatenation, so 64524463 is a term.
PROG
(Python)
from itertools import count, islice
from sympy import sqrt_mod
def A116327_gen(): # generator of terms
for j in count(0):
b = 10**j
a = b*10+1
for k in sorted(sqrt_mod(21, a, all_roots=True)):
if a*(b-5) <= k**2-21 < a*(a-6) and k>4:
yield k-4
A116327_list = list(islice(A116327_gen(), 20)) # Chai Wah Wu, Feb 21 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved