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A144378 Initial term of a series of exactly n consecutive non-Niven (or Harshad) numbers. 1
11, 22, 37, 136, 13, 64, 73, 163, 91, 1730, 289, 1639, 379, 1660, 2737, 919, 559, 14878, 7561, 5671, 9753, 2890, 7777, 4888, 5785, 5590, 27973, 47872, 28681, 22681, 3785, 36184, 46281, 71281, 6481, 48952, 48763, 64978, 119773, 69782, 77881, 55973 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Multiples of 18 seem to be the high water marks, while terms of the form 18n - 1 seem to be the valleys of this sequence.

Many terms end in '81' for some reason.

This sequence is analog to A060159 with non-Niven numbers.

This sequence is infinite, as opposed as A060159.

LINKS

Klaus Brockhaus, Table of n, a(n) for n=1..125

Eric Weisstein's World of Mathematics, Harshad Number

EXAMPLE

a(5) = 13 since 13, 14, 15, 16 and 17 are all non-Niven numbers and this is the first occurrence of exactly 5 non-Niven numbers.

PROG

(PARI) digitsum(n) = {local(s=0); while(n, s+=n%10; n\=10); s}

{m=120000; z=42; w=vector(z); n=1; while(n<=m, while(n%digitsum(n)==0, n++); a=n; c=0; while(n%digitsum(n)>0, n++; c++); if(c<=z&&w[c]==0, w[c]=a)); j=1; while(j<=z&&w[j]>0, print1(w[j], ", "); j++)} /* Klaus Brockhaus, Sep 24 2008 */

CROSSREFS

Cf. A005349, A082516, A060159, A144261, A144262.

Sequence in context: A109016 A084025 A061157 * A026037 A266088 A122613

Adjacent sequences:  A144375 A144376 A144377 * A144379 A144380 A144381

KEYWORD

base,hard,nonn

AUTHOR

Sergio Pimentel, Sep 18 2008

EXTENSIONS

a(2), a(22), a(42) corrected by Klaus Brockhaus, Sep 24 2008

STATUS

approved

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Last modified February 25 22:44 EST 2018. Contains 299662 sequences. (Running on oeis4.)