OFFSET
1,1
FORMULA
EXAMPLE
a(1) = 3 * 6 = 18.
a(2) = 63 * 36 = 2268.
a(3) = 3363 * 6636 = 22316868.
a(4) = 66663363 * 33336636 = 2222332266866868.
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a(1) = 18 = 18 - 2 * 0 + 0 * 10^1.
a(2) = 2268 = 2188 - 2 * 10 + 1 * 10^2.
a(3) = 22316868 = 22218888 - 2 * 1010 + 10 * 10^4.
a(4) = 2222332266866868 = 2222222188888888 - 2 * 11011010 + 1101 * 10^8.
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 15 2019
STATUS
approved