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A050987
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Number of n-digit left-truncatable primes.
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18
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4, 11, 39, 99, 192, 326, 429, 521, 545, 517, 448, 354, 276, 212, 117, 72, 42, 24, 13, 6, 5, 4, 3, 1, 0
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OFFSET
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1,1
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COMMENTS
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The sequence is well defined for any positive integer, with a(n) = 0 for n >= 25. But it makes sense to consider it to be full & finite. - M. F. Hasler, Nov 07 2018
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LINKS
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Table of n, a(n) for n=1..25.
I. O. Angell and H. J. Godwin, On Truncatable Primes, Math. Comput. 31, 265-267, 1977.
P. De Geest, The list of 4260 left-truncatable primes
Eric Weisstein's World of Mathematics, Truncatable Prime.
Index entries for sequences related to numbers of primes in various ranges
Index entries for sequences related to truncatable primes
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PROG
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(PARI) A050987=vector(25, n, #p=concat(apply(p->select(isprime, vector(9, i, i*10^(n-1)+p)), if(n>1, p)))) \\ M. F. Hasler, Nov 07 2018
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CROSSREFS
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Cf. A033664, A024785, A032437, A020994, A024770, A052023, A052024, A052025, A050986.
Sequence in context: A149257 A255706 A203161 * A137191 A106269 A126758
Adjacent sequences: A050984 A050985 A050986 * A050988 A050989 A050990
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KEYWORD
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base,nonn,easy,fini,full
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AUTHOR
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Eric W. Weisstein
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EXTENSIONS
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Edited by Ray Chandler, Mar 13 2007
a(25) = 0 added by M. F. Hasler, Nov 07 2018
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STATUS
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approved
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