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%I #16 Feb 19 2024 19:45:35
%S 8,98,426,571,725,844,998,7808,9998,36363,63634,99998,326732,673265,
%T 999998,4545452,5454545,9999998,47058821,52941176,99999998,331983805,
%U 332667332,384615384,422892896,475524475,524475522,577107101,615384613,667332665,668016192,719964244
%N Numbers k such that k*(k+4) gives the concatenation of two numbers m and m-3.
%H Chai Wah Wu, <a href="/A116267/b116267.txt">Table of n, a(n) for n = 1..10000</a>
%o (Python)
%o from itertools import count, islice
%o from sympy import sqrt_mod
%o def A116267_gen(): # generator of terms
%o for j in count(0):
%o b = 10**j
%o a = b*10+1
%o for k in sorted(sqrt_mod(1,a,all_roots=True)):
%o if a*(b+3) <= k**2-1 < a*(a+2):
%o yield k-2
%o A116267_list = list(islice(A116267_gen(),20)) # _Chai Wah Wu_, Feb 19 2024
%Y Cf. A116136, A116260, A116266, A116268, A116275.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, Feb 06 2006
%E a(29)-a(32) from _Chai Wah Wu_, Feb 19 2024