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%I #32 Apr 21 2022 13:10:18
%S 1,1,1,1,2,1,1,2,2,3,1,2,4,2,2,2,2,1,5,4,2,4,2,4,6,2,3,3,4,2,6,2,2,6,
%T 8,4,2,4,2,4,8,4,2,1,3,6,2,10,2,6,6,4,2,4,6,2,10,2,4,2,12,12,4,2,4,6,
%U 2,2,8,5,1,6,6,2,6,4,2,6,4,14,4,2,4,14,6,6,4,2,4,6,2,6,6,6,4,6,8,4,8,10,2,10
%N First differences of sequence of consecutive prime powers (A000961).
%C a(n) = 1 iff A000961(n) = A006549(k) for some k. - _Reinhard Zumkeller_, Aug 25 2002
%C Also run lengths of distinct terms in A070198. - _Reinhard Zumkeller_, Mar 01 2012
%H Michael B. Porter, <a href="/A057820/b057820.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A000961(n+1) - A000961(n).
%e Odd differences arise in pairs in neighborhoods of powers of 2, like {..,2039,2048,2053,..} gives {..,11,5,..}
%p A057820 := proc(n)
%p A000961(n+1)-A000961(n) ;
%p end proc: # _R. J. Mathar_, Sep 23 2016
%t Map[Length, Split[Table[Apply[LCM, Range[n]], {n, 1, 150}]]] (* _Geoffrey Critzer_, May 29 2015 *)
%t Join[{1},Differences[Select[Range[500],PrimePowerQ]]] (* _Harvey P. Dale_, Apr 21 2022 *)
%o (PARI) isA000961(n) = (omega(n) == 1 || n == 1)
%o n_prev=1;for(n=2,500,if(isA000961(n),print(n-n_prev);n_prev=n)) \\ _Michael B. Porter_, Oct 30 2009
%o (Haskell)
%o a057820_list = zipWith (-) (tail a000961_list) a000961_list
%o -- _Reinhard Zumkeller_, Mar 01 2012
%Y Cf. A000961, A036616, A001223.
%K nonn
%O 1,5
%A _Labos Elemer_, Nov 08 2000
%E Offset corrected and b-file adjusted by _Reinhard Zumkeller_, Mar 03 2012
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