A116327 k times k+8 gives the concatenation of two numbers m and m+5.

79, 35475530, 41357883, 58642110, 64524463, 3317813164402425001808, 3762581663871761671881, 4019782237714250566387, 4464550737183587236460, 5535449262816412763533, 5980217762285749433606, 6237418336128238328112

Offset

1,1

Links

Table of n, a(n) for n=1..12.

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

Cf. A116196, A116320, A116326, A116328, A116333.

Sequence in context: A265465 A138917 A265589 * A060711 A128472 A243432

Adjacent sequences: A116324 A116325 A116326 * A116328 A116329 A116330

Keyword

nonn,base

Author

Giovanni Resta, Feb 06 2006

Status

approved