A050986 - OEIS

%I #27 Feb 16 2025 08:32:41

%S 4,9,14,16,15,12,8,5,0

%N Number of n-digit right-truncatable primes.

%C Right-truncatable means that the integer part of successive divisions by 10 always yields primes (or zero). - _M. F. Hasler_, Nov 07 2018

%H Jens Kruse Andersen, <a href="http://primerecords.dk/right-truncatable.txt">Right-truncatable primes</a>

%H I. O. Angell and H. J. Godwin, <a href="http://dx.doi.org/10.1090/S0025-5718-1977-0427213-2">On Truncatable Primes</a>, Math. Comput. 31, 265-267, 1977.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TruncatablePrime.html">Truncatable Prime.</a>

%H <a href="/index/Tri#tprime">Index entries for sequences related to truncatable primes</a>

%H <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a>

%o (PARI) A050986=vector(9, n, #p=concat(apply(t->primes([t, t+1]*10), if(n>1, p)))) \\ _M. F. Hasler_, Nov 07 2018

%Y Cf. A033664, A024785, A032437, A020994, A024770, A052023, A052024, A052025, A050987.

%K base,nonn,easy,fini,full

%O 1,1

%A _Eric W. Weisstein_

%E Edited by _Ray Chandler_, Mar 13 2007

%E a(9) = 0 added by _M. F. Hasler_, Nov 07 2018