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%I #15 Oct 16 2024 22:26:30
%S 2,3,5,7,1,1,1,1,2,2,3,3,4,4,4,5,5,6,6,7,7,7,8,8,9,1,1,1,1,1,1,1,1,1,
%T 1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,
%U 3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5
%N Initial digits of prime numbers.
%H Vincenzo Librandi, <a href="/A077648/b077648.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A000030(A000040(n)).
%t Table[First[IntegerDigits[Prime[n]]], {n, 1, 120}]
%o (Magma) [Intseq(p)[#Intseq(p)]: p in PrimesUpTo(600)]; // _Bruno Berselli_, Feb 14 2013
%o (PARI) a(n) = digits(prime(n))[1]; \\ _Michel Marcus_, Feb 11 2017
%o (Python)
%o from sympy import prime
%o def A077648(n): return int(str(prime(n))[0]) # _Chai Wah Wu_, Oct 16 2024
%Y Cf. A000030, A000040.
%K base,nonn
%O 1,1
%A _Labos Elemer_, Nov 19 2002