A262511 Numbers n for which there is exactly one solution to x - d(x) = n, where d(n) is the number of divisors of n (A000005). Positions of ones in A060990.

2, 3, 4, 5, 9, 10, 12, 14, 15, 16, 18, 21, 23, 26, 30, 31, 32, 41, 42, 44, 45, 47, 53, 54, 59, 60, 61, 71, 72, 73, 76, 77, 80, 82, 83, 84, 86, 89, 90, 92, 93, 94, 95, 97, 99, 101, 104, 105, 106, 110, 115, 119, 121, 122, 127, 135, 139, 146, 148, 149, 151, 154, 158, 161, 169, 171, 173, 176, 177, 183, 186, 188, 189, 190, 191, 192, 194, 195, 199, 200, 202

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Formula

Other identities. For all n >= 1:

a(n) = A049820(A262512(n)).

Prog

(PARI)
allocatemem(123456789);
uplim = 14414400 + 504; \\ = A002182(49) + A002183(49).
v060990 = vector(uplim);
for(n=3, uplim, v060990[n-numdiv(n)]++);
A060990 = n -> if(!n, 2, v060990[n]);
uplim2 = 14414400;
n=0; k=1; while(n <= uplim2, if(1==A060990(n), write("b262511_big.txt", k, " ", n); k++); n++; );
(Scheme, with Antti Karttunen's IntSeq-library)
(define A262511 (ZERO-POS 1 1 (COMPOSE -1+ A060990)))

Crossrefs

Cf. A000005, A049820, A060990.

Cf. A262512 (gives the corresponding x).

Cf. A262510 (a subsequence).

Subsequence of A236562.

Sequence in context: A081869 A246397 A015837 * A075177 A062096 A360687

Adjacent sequences: A262508 A262509 A262510 * A262512 A262513 A262514

Keyword

nonn

Author

Antti Karttunen, Sep 25 2015

Status

approved