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A093339 Middle digits of primes with an odd number of digits. 3
2, 3, 5, 7, 0, 0, 0, 0, 1, 2, 3, 3, 3, 4, 5, 5, 6, 6, 7, 7, 8, 9, 9, 9, 9, 1, 2, 2, 2, 3, 3, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 0, 1, 1, 1, 3, 3, 4, 4, 5, 5, 6, 7, 7, 8, 8, 9, 0, 0, 1, 2, 3, 3, 3, 4, 4, 5, 6, 6, 6, 7, 8, 9, 9, 0, 0, 2, 2, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, 0, 0, 1, 1, 1, 3, 4, 4, 4, 5, 5, 6, 7, 7, 8, 9, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
LINKS
MATHEMATICA
mdp[n_]:=Module[{idn=IntegerDigits[n], len=IntegerLength[n]}, If[EvenQ[len], -1, idn[[(len-1)/2+1]]]]; Select[mdp/@Prime[Range[500]], NonNegative] (* Harvey P. Dale, Feb 26 2012 *)
PROG
(PARI) midd(n) = { forprime(x=2, n, s = Str(x); ln = length(s); if(ln<2, p=1, p = (ln-1)/2+1); if(ln%2, md = eval(mid(s, p, 1)); print1(md", ") ) ) } \ Get a substring of length n from string str starting at position s in str. mid(str, s, n) = { v =""; tmp = Vec(str); ln=length(tmp); for(x=s, s+n-1, v=concat(v, tmp[x]); ); return(v) }
CROSSREFS
Sequence in context: A261579 A270517 A124648 * A113566 A020775 A041000
KEYWORD
base,nonn
AUTHOR
Cino Hilliard, Apr 25 2004
STATUS
approved

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Last modified February 24 18:59 EST 2024. Contains 370307 sequences. (Running on oeis4.)