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A114786
Smallest prime of the form: one or more 4's followed by prime(n) (or 0 if no such prime exists).
1
0, 43, 0, 47, 44444444444444411, 44444444413, 44417, 419, 4423, 4444444429, 431, 444444437, 4441, 443, 4447, 44453, 44444459, 461, 467, 4444471, 444473, 479, 4483, 44444489, 44497, 44101, 444444103, 444444444444107, 444109, 444113, 4127
OFFSET
1,2
COMMENTS
Prime(n) is all 0's followed by prime(n). a(n) is all 4's followed by prime(n). Conjecture: No term is zero for n > 3.
a(346) = 0 or a(346) > 5000, but note a(892) = 3612. - D. S. McNeil, Feb 04 2011
EXAMPLE
a(7) = 44417, as prime(7) = 17 and both 417 and 4417 are composite.
MATHEMATICA
Table[If[n==1||n==3, 0, Select[FromDigits/@(Join[#, IntegerDigits[Prime[n]]]& /@ (Table[PadLeft[{4}, k, 4], {k, 50}])), PrimeQ, 1][[1]]], {n, 35}] (* Harvey P. Dale, Feb 03 2011 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 17 2005
EXTENSIONS
More terms from Joshua Zucker, May 06 2006
Edited by Jon E. Schoenfield, May 19 2019
STATUS
approved