A047893 - OEIS

A047893

Number of decimal digits of Euler (Zig) numbers A000364: a(n) = ceiling(log_10(|E(2n)|)), where E is Euler's E function.

0, 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

COMMENTS

Decimal order (except for powers of 10) gives the number of decimal digits. E.g., a(1)=0 and E(1)=1 of 1 digit.

REFERENCES

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

LINKS

Table of n, a(n) for n=1..62.

Eric Weisstein's World of Mathematics, Euler Number

EXAMPLE

a(4) = ceiling(log_10(1385)) = 4, E(4) = 1385, the 4th Zig-number.