A327920 The 16 pure prime dates of each year of the form concatenate(day,month) with month and day also prime numbers.

23, 53, 73, 113, 173, 193, 233, 293, 313, 37, 137, 197, 317, 211, 311, 2311

Offset

1,1

Comments

For the case of the 16, respectively 17, pure prime dates of the form concatenate(month,day) see A327918 (non-leap years) and A327919 (leap years).

Only the three months m = 3, 7, and 11 qualify. The qualifying days are for November (m = 11): d = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and for months March and July (m = 3 and 7): d = 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31.

The months m = 3, 7, 11 contribute 9, 4, 3 dates, respectively, adding to 16.

Links

Table of n, a(n) for n=1..16.

Mathematica

Select[Flatten[Table[d*10^IntegerLength[m]+m, {m, {3, 7, 11}}, {d, Prime[ Range[ 11]]}]], PrimeQ] (* Harvey P. Dale, May 24 2022 *)

Crossrefs

Cf. A055782 (first nine terms), A055783 (first four terms), A114007 (three terms starting with n = 8). A327346 (with d and m also nonprime allowed), A327918, A327919.

Sequence in context: A172034 A335655 A113912 * A055782 A338821 A104802

Adjacent sequences: A327917 A327918 A327919 * A327921 A327922 A327923

Keyword

nonn,easy,fini,full

Author

Wolfdieter Lang, Oct 08 2019

Status

approved