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A078671
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Number of times the n-th prime appears among the decimal digits of 2^(2^n) + 1, the Fermat numbers.
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0
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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, 20382, 40281, 81405, 161718, 323703, 645928
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,9
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COMMENTS
| 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
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EXAMPLE
| a(4)=1 because the 4-th prime 7 appears once in 2^2^4+1 = 65537.
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PROG
| (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))", ")); ) }
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CROSSREFS
| Cf. A000215.
Sequence in context: A077224 A059447 A190553 * A119637 A169762 A173407
Adjacent sequences: A078668 A078669 A078670 * A078672 A078673 A078674
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KEYWORD
| base,more,nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Dec 16 2002
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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
Correction of a(26). a(27)-a(31) from Robert Gerbicz (robert.gerbicz(AT)gmail.com), Nov 24 2010
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