A047893 - OEIS

A047893

Number of decimal digits of Euler (Zig) numbers A000364.

1, 1, 2, 4, 5, 7, 9, 11, 13, 15, 17, 20, 22, 25, 27, 30, 32, 35, 38, 41, 44, 46, 49, 52, 55, 58, 61, 64, 68, 71, 74, 77, 80, 84, 87, 90, 94, 97, 100, 104, 107, 111, 114, 118, 121, 125, 128, 132, 135, 139, 143, 146, 150, 154, 157, 161, 165, 168, 172, 176, 180, 183

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OFFSET

1,3

REFERENCES

J. Peters and J. Stein, Mathematische Tafeln, Revised Russian Edition, Moscow, 1968.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Euler Number.

FORMULA

a(n) = A055642(A000364(n)) = floor(log_10(|E(2n)|)) + 1 for n >=2, where E is Euler's E function.

EXAMPLE

a(4) = floor(log_10(1385)) + 1 = 4, E(4) = 1385, the 4th Euler number.