A098102 a(n) = 2^(prime(n) - 1) - 1 where prime(n) is the n-th prime.
1, 3, 15, 63, 1023, 4095, 65535, 262143, 4194303, 268435455, 1073741823, 68719476735, 1099511627775, 4398046511103, 70368744177663, 4503599627370495, 288230376151711743, 1152921504606846975
Offset: 1
Keywords
Examples
For n = 3; prime(3) = 5, a(3) = 2^(5-1) - 1 = 15.
Programs
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Magma
[2^(NthPrime(n)-1) - 1: n in [1..18]]; // Jaroslav Krizek, Jan 02 2015
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Mathematica
Table[2^(Prime[n] - 1) - 1, {n, 20}] -
PARI
a(n) = 2^(prime(n)-1) - 1; \\ Michel Marcus, Jan 13 2023
Extensions
Edited and extended by Robert G. Wilson v, Sep 23 2004
Definition and example corrected by Jaroslav Krizek, Jan 02 2015
Name edited by Michel Marcus, Jan 13 2023