A280800 -id:A280800 - cp's OEIS frontend

A280815 a(n) = A049502(cototient(n)).

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 3, 0, 0, 1, 2, 2, 0, 0, 3, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 2, 0, 0, 3, 0, 0, 4, 0, 0, 4, 0, 0, 2, 0, 1, 4, 0, 3, 1, 4, 0, 0, 0, 3, 2, 4, 1, 3, 0, 0, 2, 6, 0, 0, 4, 4, 0, 0, 0, 2, 2, 0, 1, 0, 3, 0, 0, 0, 3, 0, 0, 3, 0, 0, 1, 3, 0, 4, 0

Offset: 1

Indranil Ghosh, Jan 08 2017

nonn

a(n) = major index (2nd definition) of cototient(n), where cototient(n) = n - phi(n).

			For n = 30, cototient(n) = 22 and major index (2nd definition) of 22 is 3. So, a(n) = 3.

Indranil Ghosh, Table of n, a(n) for n = 1..10000
Indranil Ghosh, Python Program to generate the sequence

Cf. A049502, A051953, A280726, A280799, A280800.

a(n) = A049502(A051953(n)).

A280817 a(n) = A049501(sigma(n)).

Original entry on oeis.org

0, 0, 1, 0, 2, 2, 1, 0, 2, 5, 2, 3, 3, 2, 2, 0, 5, 1, 4, 9, 1, 5, 2, 4, 0, 9, 4, 3, 4, 5, 1, 0, 2, 7, 2, 5, 6, 4, 3, 11, 9, 2, 5, 9, 7, 5, 2, 5, 3, 6, 5, 8, 7, 4, 5, 4, 4, 11, 4, 9, 5, 2, 6, 0, 9, 5, 6, 6, 2, 5, 5, 2, 11, 9, 5, 7, 2, 9, 4, 13, 4, 6, 9, 3, 7, 7, 4, 11, 11, 15, 3, 9, 1, 5, 4, 6, 8, 9, 7, 7, 8, 7, 6, 13, 2, 11, 7, 7, 8

Offset: 1

Indranil Ghosh, Jan 08 2017

nonn

a(n) = major index (1st definition) of the sum of the divisors of n, i.e., sigma(n).

			For n = 10, sigma(n) = 18 and major index (1st definition) of 18 is 5. So, a(10) = 5.

Indranil Ghosh, Table of n, a(n) for n = 1..10000
Indranil Ghosh, Python Program to generate the sequence

Cf. A049501, A000203, A280726, A280800.

Table[Total@ Flatten@ Position[Partition[IntegerDigits[DivisorSigma[1, n], 2], 2, 1], {1, 0}], {n, 120}] (* Michael De Vlieger, Jan 10 2017, after Harvey P. Dale at A049501 *)

a(n) = A049501(A000203(n)).

cp's OEIS Frontend

A280815 a(n) = A049502(cototient(n)).

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