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A235397 The first term of the least sequence of n consecutive Moran numbers. 4

%I

%S 18,152,3031,21481224,25502420,4007565001480,2196125475223740,

%T 905295493763807066010

%N The first term of the least sequence of n consecutive Moran numbers.

%C A number n is a Moran number if n divided by the sum of its decimal digits is prime.

%C From _Amiram Eldar_, Apr 25 2020: (Start)

%C _Jens Kruse Andersen_ found that a(7) <= 2196125475223740 and a(8) <= 905295493763807066010 (see Rivera link).

%C Since Moran numbers (A001101) are also Niven numbers (A005349), this sequence is finite with no more than 20 terms (see A060159). (End)

%C a(9) <= 270140199032572375590810. - _Giovanni Resta_, Apr 30 2020

%H Giovanni Resta, <a href="http://www.numbersaplenty.com/set/Moran_number/">Moran numbers</a>

%H Carlos Rivera, <a href="https://www.primepuzzles.net/puzzles/puzz_728.htm">Puzzle 728. Consecutive Moran numbers</a>, The Prime Puzzles & Problems Connection.

%e a(6) = 4007565001480 because

%e 4007565001480 = 40 * 100189125037,

%e 4007565001481 = 41 * 97745487841,

%e 4007565001482 = 42 * 95418214321,

%e 4007565001483 = 43 * 93199186081,

%e 4007565001484 = 44 * 91081022761,

%e 4007565001485 = 45 * 89057000033.

%o (PARI) isA001101(n)=(k->denominator(k)==1&&isprime(k))(n/sumdigits(n))

%o a(n)=my(k=n); while(1, forstep(i=k,k-n+1,-1, if(!isA001101(i), k=i+n; next(2))); return(k-n+1)) \\ _Charles R Greathouse IV_, Jan 10 2014

%Y Cf. A001101, A060159, A085775.

%K nonn,hard,base,fini,more

%O 1,1

%A _Carlos Rivera_, Jan 09 2014

%E a(7)-a(8) from _Giovanni Resta_, Apr 27 2020

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Last modified July 15 04:00 EDT 2020. Contains 335762 sequences. (Running on oeis4.)