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A254338 Initial digits of A254143 in decimal representation. 8
1, 4, 7, 1, 2, 3, 3, 4, 6, 1, 1, 2, 2, 2, 3, 3, 3, 4, 6, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 6, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A000030(A254143(n));

also initial digits of A254323: a(n) = A000030(A254323(n)).

all terms are of the form u*v mod 10, where u <= v and belonging to {1,3,4,6,7}, the distinct elements of A254397:

length of k-th run of consecutive 1s = A005993(k-2), k > 1;

length of k-th run of consecutive 2s = k*(k+1)/2 = A000217(k), k >= 1;

length of k-th run of consecutive 3s = k+1, k >= 1;

length of k-th run of consecutive 4s = A065033(k-1);

n with a(n) = 4: A237424(n) = (10^a+10^b+1)/3 with b = 0, see also A093137, A133384;

n with a(n) = 6: A237424(n) = (10^a+10^b+1)/3 with a = b; A005994(a(n)) = 6 for n > 1; see also A199682;

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

PROG

(Haskell)

a254338 = a000030 . a254143

(PARI) listA237424(lim)=my(v=List(), a, t); while(1, for(b=0, a, t=(10^a+10^b+1)/3; if(t>lim, return(Set(v))); listput(v, t)); a++)

do(lim)=my(v=List(), u=listA237424(lim), t); for(i=1, #u, for(j=1, i, t=u[i]*u[j]; if(t>lim, break); listput(v, t))); apply(n->digits(n)[1], Set(v)) \\ Charles R Greathouse IV, May 13 2015

CROSSREFS

Cf. A254143, A254323, A000030, A254339, A005993, A000217, A065033.

Sequence in context: A195789 A021959 A188735 * A197723 A186191 A256507

Adjacent sequences:  A254335 A254336 A254337 * A254339 A254340 A254341

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller, Feb 27 2015

STATUS

approved

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Last modified October 21 16:33 EDT 2018. Contains 316427 sequences. (Running on oeis4.)