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A135613 Initial digit of Mersenne primes A000668. 6
3, 7, 3, 1, 8, 1, 5, 2, 2, 6, 1, 1, 6, 5, 1, 1, 4, 2, 1, 2, 4, 3, 2, 4, 4, 4, 8, 5, 5, 5, 7, 1, 1, 4, 8, 6, 1, 4, 9, 1, 2, 1, 3, 1, 2, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = A000030(A000668(n)). - Omar E. Pol, Jul 04 2019
EXAMPLE
a(4)=1 because the 4th Mersenne prime A000668(4) is 127 and the initial digit of 127 is 1.
MATHEMATICA
lst = {* the list of terms in A000043 *}; f[n_] := Block[{pn = 2^n - 1}, Quotient[pn, 10^Floor[ Log[10, pn]] ]]; f@# & /@ lst (* Robert G. Wilson v, Apr 01 2008 *)
IntegerDigits[#][[1]]&/@(2^#-1&/@MersennePrimeExponent[Range[47]]) (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 04 2019 *)
CROSSREFS
Sequence in context: A256978 A296442 A021272 * A019973 A010623 A283245
KEYWORD
nonn,base,more
AUTHOR
Omar E. Pol, Mar 01 2008
EXTENSIONS
More terms from Robert G. Wilson v, Apr 01 2008
a(40)-a(44) from David Radcliffe, Jan 21 2016
a(45)-a(47) from Ivan Panchenko, Apr 11 2018
STATUS
approved

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Last modified June 17 18:36 EDT 2024. Contains 373463 sequences. (Running on oeis4.)