A173550 a(n) = k smallest exponent of N = 2^k of first prime(1) = 2 where string "p(1) ... p(n)" appears in the decimal representation of N (n=1,2,...).

1, 41, 81, 256, 2810, 19680, 131516, 1812049

Offset

1,2

References

Julian Havil, Impossible?: Surprising Solutions to Counterintuitive Conundrums, Princeton University Press 2008

Links

Table of n, a(n) for n=1..8.

Example

n=1: 2^1 = 2
n=2: 2^41 = 2199023255552, "23" appears on decimals 6-7
n=3: 2^81 = 2417851639229258349412352, "235" appears on decimals 22-24
n=4: 2^256 has 78 decimals, "2357" appears on decimals 20-23
2^256 = 115792089237316195423570985008687907853269984665640564039457584007913129639936

Crossrefs

Cf. A000079, A018802, A171132, A171242, A171489, A171652, A171768

Sequence in context: A044488 A335482 A375138 * A136072 A098061 A141898

Adjacent sequences: A173547 A173548 A173549 * A173551 A173552 A173553

Keyword

nonn,base

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Feb 21 2010

Extensions

Extended and edited by Hans Havermann, Mar 20 2010

Status

approved