A115443
Numbers whose square is the concatenation of two numbers k and k-4.
Original entry on oeis.org
81, 8157, 9801, 467347, 532654, 998001, 76450589, 99980001, 7801738415, 8593817623, 9208120793, 9999800001, 346667333467, 401461854015, 598538145986, 653332666534, 945207479453, 999998000001, 48349470735060
Offset: 1
Cf.
A030467,
A106497,
A115432,
A115427,
A115438,
A115439,
A115440,
A115441,
A115442,
A115444,
A115445,
A115446,
A115447.
A116104
Numbers k such that k concatenated with k-8 gives the product of two numbers which differ by 4.
Original entry on oeis.org
65, 6653, 9605, 218413, 283720, 996005, 58446925, 99960005, 6086712229, 7385370133, 8478948853, 9999600005, 120178240093, 161171620229, 358247912200, 426843573160, 893417179213, 999996000005, 23376713203604
Offset: 1
9999600005//9999599997 = 9999799999 * 9999800003, where // denotes concatenation.
A116121
Numbers k such that k concatenated with k-5 gives the product of two numbers which differ by 2.
Original entry on oeis.org
65, 6653, 9605, 218413, 283720, 996005, 58446925, 99960005, 6086712229, 7385370133, 8478948853, 9999600005, 120178240093, 161171620229, 358247912200, 426843573160, 893417179213, 999996000005, 23376713203604
Offset: 1
9999600005//9999600000 = 9999800000 * 9999800002, where // denotes concatenation.
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