OFFSET
1,2
FORMULA
a(n) ~ c * 2^(n*(n+1)/2), where c = 0.3997494420337372941776146353642774...
MATHEMATICA
RecurrenceTable[{a[n]==(2^n-1)*a[n-1]+1, a[1]==1}, a, {n, 1, 15}]
PROG
(PARI) a(n) = if (n==1, 1, (2^n-1)*a(n-1) + 1); \\ Michel Marcus, Sep 30 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Oct 10 2016
STATUS
approved
