cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A352257 Sum of all parts of all partitions of n into an odd number of consecutive parts.

Original entry on oeis.org

1, 2, 3, 4, 5, 12, 7, 8, 18, 10, 11, 24, 13, 14, 45, 16, 17, 36, 19, 40, 42, 22, 23, 48, 50, 26, 54, 56, 29, 90, 31, 32, 66, 34, 105, 72, 37, 38, 78, 80, 41, 126, 43, 44, 180, 46, 47, 96, 98, 100, 102, 52, 53, 162, 110, 112, 114, 58, 59, 180, 61, 62, 252, 64, 130, 198
Offset: 1

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Author

Omar E. Pol, Mar 09 2022

Keywords

Comments

a(n) is n times the number of partitions of n into an odd number of consecutive parts.

Examples

			For n = 15 the partitions of 15 into an odd number of consecutive parts are [15], [6, 5, 4] and [5, 4, 3, 2, 1], so a(15) = 15 + 6 + 5 + 4 + 5 + 4 + 3 + 2 + 1 = 15*3 = 45.
		

Crossrefs

Programs

  • PARI
    a(n) = my(q = sqrt(2*n)); n*sumdiv(n, d, (d%2) && (d < q)); \\ Michel Marcus, Mar 11 2022; after A082647

Formula

a(n) = n*A082647(n).
a(n) = A245579(n) - A352505(n). - Omar E. Pol, Mar 19 2022