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A101784
Primes which remain prime after omitting maximal digit.
1
23, 29, 37, 43, 53, 59, 73, 79, 83, 97, 113, 131, 137, 139, 151, 163, 173, 179, 181, 191, 193, 197, 199, 211, 233, 239, 263, 283, 293, 311, 313, 317, 331, 379, 397, 419, 431, 439, 443, 461, 463, 479, 487, 491, 503, 523, 541, 563, 593, 599, 613, 617, 619, 631
OFFSET
1,1
COMMENTS
If there are several maximal digits, first from left is omitted.
LINKS
MAPLE
filter:= proc(p) local r, q, L, j;
if not isprime(p) then return false fi;
L:= convert(p, base, 10);
r:= max(L);
for j from nops(L) by -1 do
if L[j] = r then q:= p mod 10^(j-1) + floor(p/10^j)*10^(j-1); return isprime(q) fi
od;
end proc;
MATHEMATICA
omit[d_, list_] := Module[{aux = {}, len = Length[list]}, Do[If[list[[i]] == d, none, aux = Join[aux, {list[[i]]}]], {i, len}]; aux]; maxomit[n_] := omit[Max[IntegerDigits[Prime[n]]], IntegerDigits[Prime[n]]]; convert[lis_] := Sum[Reverse[lis][[i]] 10^(i - 1), {i, 1, Length[lis]}]; Table[If[PrimeQ[convert[maxomit[n]]], Prime[n], 0], {n, 1, 300}] //Union //Rest (* Jose Grau, Feb 17 2010 *)
CROSSREFS
Sequence in context: A375595 A180066 A353286 * A101802 A363074 A156983
KEYWORD
base,easy,nonn
AUTHOR
Zak Seidov, Jan 27 2005
STATUS
approved