%I A057820
%S A057820 1,1,1,1,2,1,1,2,2,3,1,2,4,2,2,2,2,1,5,4,2,4,2,4,6,2,3,3,4,2,6,2,2,6,8,
               4,
%T A057820 2,4,2,4,8,4,2,1,3,6,2,10,2,6,6,4,2,4,6,2,10,2,4,2,12,12,4,2,4,6,2,2,8,
%U A057820 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 A057820 First differences of sequence of consecutive prime powers (A000961).
%C A057820 a(n) = 1 iff A000961(n) = A006549(k) for some k. - Reinhard Zumkeller 
               (reinhard.zumkeller(AT)gmail.com), Aug 25 2002
%F A057820 a(n)=A000961(n+1)-A000961(n)
%e A057820 Odd differences arise in pairs in neighborhoods of powers of 2, like 
               {..,2039,2048,2053,..} gives {..,11,5,..}
%o A057820 Contribution from Michael Porter (michael_b_porter(AT)yahoo.com), Oct 
               30 2009: (Start)
%o A057820 (PARI) isA000961(n) = (omega(n) == 1 | n == 1)
%o A057820 n_prev=1;for(n=2,500,if(isA000961(n),print(n-n_prev);n_prev=n)) (End)
%Y A057820 Cf. A000961, A036616, A001223.
%Y A057820 Sequence in context: A047060 A050167 A047050 this_sequence A054012 A062083 
               A133114
%Y A057820 Adjacent sequences: A057817 A057818 A057819 this_sequence A057821 A057822 
               A057823
%K A057820 nonn
%O A057820 0,5
%A A057820 Labos E. (labos(AT)ana.sote.hu), Nov 08 2000