

A074801


a(n) is the sum of the nth row of the triangle formed by replacing each m in Pascal's triangle with sigma(m).


4



1, 2, 5, 10, 28, 50, 116, 178, 528, 1282, 2794, 4778, 10594, 17166, 33426, 60242, 183072, 304202, 759716, 1288642, 2965286, 6352098, 11776586, 18326642, 48714362, 95769336, 172377654, 417138342, 1004225842, 1633822142, 3266821106, 4706920002, 16520601024
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OFFSET

0,2


LINKS



FORMULA

a(n) >= 2^n with equality for n <= 2.  Michel Marcus, Mar 19 2017


EXAMPLE

The third row of Pascal's triangle is 1 3 3 1. When each n here is replaced by sigma(n), the row becomes 1 4 4 1 with a sum of 10, so a(3) = 10.


MATHEMATICA

a[n_] := Sum[DivisorSigma[1, Binomial[n, i]], {i, 0, n}]; Table[a[i], {i, 1, 21}]


PROG

(PARI) a(n) = sum(k=0, n, sigma(binomial(n, k))); \\ Michel Marcus, Mar 17 2017


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS

Offset changed to 0 by Editors, Mar 19 2017


STATUS

approved



