|
Search: id:A078671
|
|
|
| A078671 |
|
Number of times the n-th prime appears among the decimal digits of 2^(2^n) + 1, the Fermat numbers. |
|
+0
1
|
|
| 0, 0, 1, 1, 0, 0, 1, 1, 2, 4, 9, 14, 21, 46, 112, 204, 374, 809, 1586, 3237, 6385, 12539, 25637, 50603, 100891, 20191
(list; graph; listen)
|
|
|
OFFSET
|
1,9
|
|
|
COMMENT
|
Conjectures: Is a(n) monotonically increasing for n > 4? Does lim{n->inf} a(n)/a(n+1) = 0.5? - Ryan Propper (rpropper(AT)cs.stanford.edu), Jan 04 2008
|
|
EXAMPLE
|
a(4)=1 because the 4-th prime 7 appears once in 2^2^4+1 = 65537.
|
|
PROGRAM
|
(PARI) \ Type ff to run. {mcf(d, n)=local(a, c=0, L); L=length(Str(d)); if(L>1, a=2, a=1); while(n>0, if(n%(10^a)==d, n=floor(n/10); c++, n=floor(n/10); )); c } {ff()=local(a); print("Enter an ending value <= 25: "); a=input(); if(a>25, error("Input not valid, try again."), for(n=1, a, print1(mcf(prime(n), (2^2^n+1))", ")); ) }
|
|
CROSSREFS
|
Cf. A000215.
Sequence in context: A085901 A077224 A059447 this_sequence A119637 A113862 A036277
Adjacent sequences: A078668 A078669 A078670 this_sequence A078672 A078673 A078674
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
Jason Earls (zevi_35711(AT)yahoo.com), Dec 16 2002
|
|
EXTENSIONS
|
More terms from Ryan Propper (rpropper(AT)cs.stanford.edu), Jan 04 2008
a(24)-a(26) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 17 2008
|
|
|
Search completed in 0.002 seconds
|
