login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A268287 a(n) shows how many times the sum of the hours and minutes is prime in an n-hour period starting from midnight. 0
0, 17, 34, 52, 69, 85, 101, 116, 131, 146, 161, 176, 191, 206, 221, 236, 251, 266, 281, 295, 309, 323, 337, 351, 365, 382, 399, 417, 434, 450, 466, 481, 496, 511, 526, 541, 556, 571, 586, 601, 616, 631, 646, 660, 674, 688, 702, 716, 730, 747, 764, 782, 799, 815, 831, 846, 861, 876, 891 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Partial sums of the sequence formed by repeating [17, 17, 18, 17, 16, 16, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 14, 14, 14, 14, 14, 14]. - Michel Marcus, Feb 01 2016

LINKS

Table of n, a(n) for n=0..58.

EXAMPLE

In the first one-hour period, i.e. between 0:00 and 0:59, there are PrimePi(59) - PrimePi[0] = 17 primes, therefore a(1) = 17.

MATHEMATICA

days[n_]:=Floor[n/24]; hours[n_]:=n-24*days[n];

len[n_]:=If[hours[n]==0, 0, Length[Select[Flatten[Table[Table[h+m, {m, 0, 59}], {h, 0, hours[n]-1}]], PrimeQ]]];

total[n_]:=365*days[n]+len[n];

total/@Range[0, 100]

CROSSREFS

Cf. A000040.

Sequence in context: A033014 A070814 A188290 * A249988 A098365 A033899

Adjacent sequences:  A268284 A268285 A268286 * A268288 A268289 A268290

KEYWORD

easy,nonn

AUTHOR

Ivan N. Ianakiev, Jan 30 2016

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 20 12:38 EST 2019. Contains 320327 sequences. (Running on oeis4.)