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a(n) = index of first n in A262680; positions of records in A262680.
4

%I #8 Oct 03 2015 08:46:29

%S 0,1,4,169,324,1521,125316,126025,425104,1713481,1716100,4959529,

%T 24760576

%N a(n) = index of first n in A262680; positions of records in A262680.

%C All terms are squares (A262688 gives the square roots).

%C The even and odd terms alternate.

%o (PARI)

%o allocatemem((2^31)+(2^30));

%o uplim = 2^25;

%o v262680 = vector(uplim);

%o v262680[1] = 1; v262680[2] = 0;

%o for(i=3, uplim, v262680[i] = issquare(i) + v262680[i-numdiv(i)];

%o if(!(i%65536),print1(i,", ")););

%o A262680 = n -> if(!n,n,v262680[n]);

%o n=0; k=0; while(n*n <= uplim, if(A262680(n*n)==k, write("b262687.txt", k, " ", n*n); k++); n++;);

%o (Scheme, with _Antti Karttunen_'s IntSeq-library)

%o (define A262687 (RECORD-POS 0 0 A262680))

%Y Cf. A262680, A261088, A262514.

%Y Cf. A262688 (square roots of these terms).

%K nonn,more

%O 0,3

%A _Antti Karttunen_, Oct 03 2015