A050246 Digital clock primes.

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 211, 223, 227, 229, 233, 239, 241, 251, 257, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 401, 409, 419, 421, 431, 433, 439, 443

Offset: 1

Author

Eric W. Weisstein

Keywords

• nonn
• easy
• base
• fini
• full

Comments

The number of minutes past midnight represented by each of the times here can be found in A118848. - Carl R. White, May 01 2006

Equals the first 211 terms of A229106, corresponding to interpretation as minutes and seconds what are hours and minutes here. - M. F. Hasler, Jan 09 2018

Examples

			a(143) = 1453 is shown in the last panel of Randall Munroe's Web Comic #247.
		

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..211 (full sequence)
• Randall Munroe, Factoring the time, xkcd Web Comic #247, Apr 11 2007.
• Eric Weisstein's World of Mathematics, Clock Prime.

Crossrefs

Cf. A118848, A118849, A118850, A129336, A316603.

Cf. A159911, where hours H and minutes MM must also be prime, separately.

Programs

Maple

for h from 0 to 23 do for m from 0 to 59 do t:=100*h+m: if(isprime(t))then printf("%d, ", t): fi: od: od: # Nathaniel Johnston, May 17 2011

PARI

A050246 = select( t -> t%100 < 60, primes([1,2399])) \\ M. F. Hasler, Jan 09 2018

Formula

a(n) = A118848(n) + floor(A118848(n)/60)*40. - Carl R. White, May 01 2006