A295013 - OEIS

%I #17 Jan 22 2018 03:01:38

%S 20219,20231,20261,20297,20323,20341,20347,20353,20359,20389,20507,

%T 20543,20707,20717,20719,20731,20743,20747,20753,20759,20771,20773,

%U 20789,21107,21143,21179,21313,21317,21319,21323,21341,21347,21379,21383,21397,21713

%N Prime time primes on 6-digit clocks, second definition: primes of the form HMMSS where H, MM, SS are primes, H < 24, MM and SS < 60.

%C A subsequence and variant of A229106, where the individual digit groups are not required to be primes. Also a subsequence (namely, the prime terms) of A295014, where H, MM and SS must be primes, but not the concatenation HMMSS.

%C See A295000 for the subsequence of terms for which the number of seconds after midnight (3600*H + 60*MM + SS, listed in A295003) is also prime.

%H M. F. Hasler, <a href="/A295013/b295013.txt">Table of n, a(n) for n = 1..1211</a> (complete sequence).

%t With[{s = Prime@ Range@ PrimePi@ 60}, Select[FromDigits@ Flatten[PadLeft[IntegerDigits[#], 2] & /@ #] & /@ Tuples@ {TakeWhile[s, # < 24 &], s, s}, PrimeQ]] (* _Michael De Vlieger_, Jan 21 2018 *)

%o (PARI) is_A295013(n)=apply(isprime,digits(n,100))==[1,1,1]&&n<24e4&&isprime(n)

%o A295013 = select( is_A295013, primes([20000,240000]))

%Y Cf. A050246, A159911, A229106; A118848, A118849, A118850.

%Y Cf. A295014, A295003, A295011, A295000, A295002.

%K nonn,base,fini,full

%O 1,1

%A _M. F. Hasler_, Jan 09 2018