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A186075
Irregular triangle, read by rows, of primes with suffix n and digits "9" prepended, otherwise 0.
0
0, 0, 0, 0, 0, 0, 97, 997, 0, 0, 0, 911, 0, 0, 0, 0, 0, 0, 0, 919, 0, 0, 0, 0, 0, 0, 0, 0, 0, 929, 9929, 99929, 0, 0, 0, 0, 0, 0, 0, 937, 0, 0, 0, 941, 9941, 0, 0, 0, 0, 0, 947, 0, 0, 0, 0, 0, 953, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 967, 9967, 0, 0, 0, 971, 0, 0, 0, 0, 0, 977
OFFSET
1,7
COMMENTS
Row n ends when a composite number is found. ~
EXAMPLE
for k=1..3 , a(29, k) = {929, 9929,99929} are in the sequence.
MAPLE
with(numtheory): for n from 1 to 100 do:a0:=n:id:=0:c:=0:for k from 1 to 20
while (id=0) do:d:=length(a0):a1:=9*10^d+a0:if type(a1, prime)=true then a0:=a1:printf(`%d,
`, a0):c:=c+1:else id:=1:fi:od:if c=0 then printf(`%d, `, 0):else fi:od:
KEYWORD
nonn,base,tabf
AUTHOR
Michel Lagneau, Feb 11 2011
STATUS
approved