

A263093


Numbers whose squares are in A045765.


5



5, 6, 7, 8, 10, 14, 16, 18, 20, 22, 26, 27, 28, 34, 35, 37, 46, 47, 50, 54, 56, 58, 59, 60, 62, 67, 73, 78, 82, 85, 89, 90, 94, 95, 98, 100, 103, 104, 106, 110, 114, 116, 118, 122, 124, 125, 126, 127, 128, 130, 135, 140, 141, 142, 148, 150, 155, 158, 161, 164, 170, 172, 174, 177, 178, 182, 184, 188, 190, 199, 202, 205, 207
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Numbers n such that there is no such k for which k  d(k) = n^2, where d(k) is the number of divisors of k (A000005).
Numbers n for which A060990(n^2) = A263087(n) = 0.


LINKS

Antti Karttunen, Table of n, a(n) for n = 1..12443
A. Karttunen, Ratio a(n)/A263092(n) drawn with the help of OEIS Plot2utility


FORMULA

a(n) = A000196(A263095(n)).


PROG

(PARI)
\\ Compute A263093 and A263095 at the same time:
A060990(n) = { my(k = n + 1440, s=0); while(k > n, if(((knumdiv(k)) == n), s++); k; ); s}; \\ Hard limit 1440 is good for at least up to A002182(67) = 1102701600 as A002183(67) = 1440.
n = 1; k = 0; while((n^2)<1102701600, if((0 == A060990(n*n)), k++; write("b263093.txt", k, " ", n); write("b263095.txt", k, " ", (n*n)); ); n++; if(!(n%8192), print1(n, ", k=", k, ", ")); );
(Scheme, with Antti Karttunen's IntSeqlibrary)
(define A263093 (MATCHINGPOS 1 1 (lambda (n) (zero? (A060990 (* n n))))))
(define A263093 (ZEROPOS 1 0 A263087))


CROSSREFS

Cf. A000005, A000196, A045765, A049820, A060990, A263098.
Complement: A263092.
Positions of zeros in A263087 and positions of ones in A263088.
Cf. A263095 (the squares of these numbers).
Sequence in context: A037361 A202014 A319266 * A115839 A200259 A339746
Adjacent sequences: A263090 A263091 A263092 * A263094 A263095 A263096


KEYWORD

nonn


AUTHOR

Antti Karttunen, Oct 11 2015


STATUS

approved



