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A262687
a(n) = index of first n in A262680; positions of records in A262680.
4
0, 1, 4, 169, 324, 1521, 125316, 126025, 425104, 1713481, 1716100, 4959529, 24760576
OFFSET
0,3
COMMENTS
All terms are squares (A262688 gives the square roots).
The even and odd terms alternate.
PROG
(PARI)
allocatemem((2^31)+(2^30));
uplim = 2^25;
v262680 = vector(uplim);
v262680[1] = 1; v262680[2] = 0;
for(i=3, uplim, v262680[i] = issquare(i) + v262680[i-numdiv(i)];
if(!(i%65536), print1(i, ", ")); );
A262680 = n -> if(!n, n, v262680[n]);
n=0; k=0; while(n*n <= uplim, if(A262680(n*n)==k, write("b262687.txt", k, " ", n*n); k++); n++; );
(Scheme, with Antti Karttunen's IntSeq-library)
(define A262687 (RECORD-POS 0 0 A262680))
CROSSREFS
Cf. A262688 (square roots of these terms).
Sequence in context: A024265 A302453 A061710 * A177005 A017414 A051476
KEYWORD
nonn,more
AUTHOR
Antti Karttunen, Oct 03 2015
STATUS
approved