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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: A367608 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 July 20 17:18 EDT 2024. Contains 374459 sequences. (Running on oeis4.)