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A119298
Total number of 7's digits in the first 10^n primes.
4
2, 34, 551, 6338, 72319, 809360, 9543704, 104376285, 1136782466, 12273965395, 134080968533, 1448607569210
OFFSET
1,1
EXAMPLE
At a(1)=2 there are 2 7's digits in the first 10^1 primes.
MAPLE
A119298 := proc(n) option remember: local k, s, lim: if(n=0)then return 0:fi: lim:=10^n: s:=procname(n-1): for k from 10^(n-1)+1 to lim do s:=s+nops([SearchAll("7", convert(ithprime(k), string))]): od: return s: end: seq(A119298(n), n=1..4); # Nathaniel Johnston, May 09 2011
MATHEMATICA
Table[Count[IntegerDigits[Prime[Range[10^n]]], 7, 2], {n, 6}] (* Robert Price, May 02 2019 *)
KEYWORD
more,nonn,base
AUTHOR
Enoch Haga, May 13 2006
EXTENSIONS
Offset changed from 0 to 1 by Nathaniel Johnston, May 09 2011
a(8)-a(11) from Robert Price, Nov 05 2013
a(12) from Marek Hubal, Mar 04 2019
STATUS
approved