A055618 a(n) = A*10^(4*n-1) + B with A = 990*(10^(4*n)-1)/9999 and B = 990000*(10^(4*n-4)-1)/9999 + 100.
990100, 99009900990100, 9900990099009900990100, 990099009900990099009900990100, 99009900990099009900990099009900990100, 9900990099009900990099009900990099009900990100, 990099009900990099009900990099009900990099009900990100
Offset: 1
Examples
a(2) = (990*(10^8-1)/9999)*10^7 + 990000*(10^4-1)/9999 + 100 = 99009900990100 = 9900990^2 + 0990100^2.
Crossrefs
Subset of A055616.
Programs
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Maple
for n from 1 to 15 do printf(`%d,`,(990*(10^(4*n)-1)/9999)*10^(4*n-1)+990000*(10^(4*n-4)-1)/9999+100 ) od:
Extensions
One more term from James Sellers, Sep 28 2001
a(6) corrected by Sean A. Irvine, Mar 29 2022