login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A158571 Primes whose digit sum is a single-digit nonprime. 1
13, 17, 31, 53, 71, 103, 107, 211, 233, 251, 431, 503, 521, 701, 1021, 1061, 1151, 1201, 1223, 1511, 1601, 2011, 2141, 2213, 2411, 3001, 3023, 3041, 3203, 3221, 4013, 4211, 5003, 5021, 6011, 6101, 7001, 10007, 10061, 10111, 10133, 10151, 10223, 10313 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It is interesting to observe that it is hard to find (I found none) primes whose digit sum is 6. On the contrary, it is easier to find primes whose digit sum is 8.

The digit sum 6 does not occur here because a number with digit sum 6 is divisible by 3 and therefore not prime. - R. J. Mathar, Mar 26 2009

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Chris Caldwell, The First 1,000 Primes

FORMULA

Union of A062339 and A062343. - R. J. Mathar, Mar 26 2009

EXAMPLE

1061 is a prime whose digit sum is 8, which is a single-digit nonprime.

MAPLE

for i from 1 to 8 do if member(i, [1, 3, 7]) then S[1, i]:= {i} else S[1, i]:= {} fi od:

for d from 2 to 5 do

  for x from 1 to 8 do

    S[d, x]:= {};

    for y from 0 to x-1 do

      S[d, x]:= S[d, x] union map(t -> 10^(d-1)*y + t, S[d-1, x-y])

od od od:

select(isprime, S[5, 4] union S[5, 8]); # Robert Israel, Apr 14 2021

CROSSREFS

Cf. A158217.

Sequence in context: A116671 A062338 A143863 * A176882 A272403 A159614

Adjacent sequences:  A158568 A158569 A158570 * A158572 A158573 A158574

KEYWORD

base,nonn

AUTHOR

Parthasarathy Nambi, Mar 21 2009

EXTENSIONS

Extended by R. J. Mathar, Mar 26 2009

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 June 19 09:33 EDT 2021. Contains 345126 sequences. (Running on oeis4.)