A263251 - OEIS

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A263251

Odd bisection of A263087; number of solutions to x - d(x) = (2n+1)^2, where d(x) is the number of divisors of x (A000005).

2, 1, 0, 0, 2, 1, 1, 1, 1, 1, 2, 1, 1, 0, 1, 2, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 2, 0, 1, 1, 1, 1, 1, 0, 1, 0, 2, 1, 0, 1, 1, 1, 0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 0, 0, 1, 2, 2, 0, 2, 1, 0, 1, 1, 1, 2, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 3, 2, 1, 0, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 2, 0, 0, 0, 0, 1, 2, 2, 2, 2, 0, 0, 1, 0, 1, 1, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..10000

FORMULA

a(n) = A263087(2*n + 1).

PROG

(PARI)

A060990(n) = { my(k = n + 2400, s=0); while(k > n, if(((k-numdiv(k)) == n), s++); k--; ); s}; \\ Hard limit A002183(77)=2400 good for at least up to A002182(77) = 10475665200.

A263087(n) = A060990(n^2);

A263251(n) = A263087((2*n)+1);

p = 0; for(n=0, 10000, k = A263251(n); p += k; write("b263251.txt", n, " ", k); write("b263253.txt", n, " ", p)); \\ Compute A263251 and A263253 at the same time.

(Scheme) (define (A263251 n) (A263087 (+ n n 1)))

CROSSREFS

Cf. A000005, A060990, A263087, A263250.

Cf. also A263253 (partial sums).

Sequence in context: A025874 A256012 A332040 * A318370 A339742 A345164

Adjacent sequences: A263248 A263249 A263250 * A263252 A263253 A263254

KEYWORD

nonn

AUTHOR

Antti Karttunen, Nov 07 2015

STATUS

approved