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!)
A292566 Primes that can be reached with their prime-index, if you start with the prime-index and use iterations of A062028. 0
2, 11, 107, 191, 587, 719, 1061, 1171, 1181, 1259, 1327, 1487, 1597, 1619, 1933, 1949, 2011, 2141, 2269, 2477, 2803, 2999, 3041, 3049, 3079, 3169, 3229, 3259, 3617, 3733, 4493, 4799, 5009, 5023, 5171, 5261, 5581, 5657, 6131, 6211, 6301, 6311, 6421, 6451, 6529 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If p is in the sequence, its index A000720(p) is not divisible by 3. - Robert Israel, Sep 19 2017

LINKS

Table of n, a(n) for n=1..45.

EXAMPLE

The prime-index of 11 is 5: 5+5=10, 10+1+0=11 -> after two iterations you reach 11, so 11 is in the sequence.

MAPLE

f:= proc(n) local t, p;

  p:= ithprime(n);

  t:= n;

  do

    t:= t + convert(convert(t, base, 10), `+`);

    if t > p then return NULL

    elif t = p then return p

    fi

  od;

end proc:

map(f, [$1..1000]); # Robert Israel, Sep 19 2017

MATHEMATICA

ok[p_] := Block[{n = PrimePi@ p}, While [n < p, n += Total@ IntegerDigits@ n]; n == p]; Select[Prime@ Range@ 600, ok] (* Giovanni Resta, Sep 19 2017 *)

PROG

(PARI) is(n) = my(x=primepi(n)); while(1, x=x+sumdigits(x); if(x==n, return(1), if(x > n, return(0))))

forprime(p=1, 7000, if(is(p), print1(p, ", "))) \\ Felix Fröhlich, Sep 19 2017

CROSSREFS

Cf. A000720, A062028, A007618, A004207.

Sequence in context: A118805 A198001 A207155 * A053988 A141314 A099933

Adjacent sequences:  A292563 A292564 A292565 * A292567 A292568 A292569

KEYWORD

nonn,base

AUTHOR

Peter Weiss, Sep 19 2017

EXTENSIONS

More terms from Felix Fröhlich, Sep 19 2017

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 March 30 10:09 EDT 2020. Contains 333125 sequences. (Running on oeis4.)