OFFSET
1,2
COMMENTS
Prime(n) is all zeros followed by prime(n).This is all sevens followed by prime(n). Conjecture: a(n) is nonzero if n >4.
The conjecture has been verified for n<100. - Joshua Albert (jba138(AT)psu.edu), Jan 20 2006
EXAMPLE
a(9) = 7723, as 723 is composite, prime(9) = 23.
MATHEMATICA
Join[{0, 73, 0, 0}, Flatten[Select[#, PrimeQ, 1]&/@Table[FromDigits[ PadLeft[ IntegerDigits[n], i, 7]], {n, Prime[Range[5, 30]]}, {i, IntegerLength[ n]+1, 100}]]] (* Harvey P. Dale, Nov 20 2013 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 18 2005
EXTENSIONS
More terms from Joshua Albert (jba138(AT)psu.edu), Jan 20 2006
STATUS
approved