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A089396
Smallest n-digit term of A089395.
2
1, 12, 106, 1018, 10312, 105502, 1197058, 11056216
OFFSET
0,2
EXAMPLE
a(3) = 256 which is the smallest 3-digit number such that 2*56 + 1 = 113, 25*6 + 1 = 151 and 256 + 1 = 257 are all prime.
MAPLE
with(combinat): ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1), j=1..nops(s))):end: for d from 1 to 7 do sch:=[seq([1, op(i), d+1], i=[[], seq([j], j=2..d)])]: for n from 10^(d-1) to 10^d-1 do sn:=convert(n, base, 10): fl:=0: for s in sch do m:=mul(j, j=[seq(ds(sn[s[i]..s[i+1]-1]), i=1..nops(s)-1)])+1: if not isprime(m) then fl:=1: break fi od: if fl=0 then printf("%d, ", n):break fi od od: # C. Ronaldo
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 10 2003
EXTENSIONS
Corrected and extended by C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
One more term (a(7)) from Harvey P. Dale, Mar 23 2019
STATUS
approved