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A107736 Pentagonal numbers that are half other pentagonal numbers. 0
35, 46651605, 62126595542551, 82734857056306152425, 110179167429819564875005515 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

FORMULA

a(n)=((A001653(4n-2)^2-1)/24

EXAMPLE

a(2)=((A001653(6)^2-1)/24=(33461^2-1)/24=46651605.

CROSSREFS

Cf. A001653, A000326.

Sequence in context: A139473 A110596 A126029 * A139474 A023929 A010113

Adjacent sequences:  A107733 A107734 A107735 * A107737 A107738 A107739

KEYWORD

nonn

AUTHOR

Franz Vrabec (franz.vrabec(AT)aon.at), Aug 26 2006

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Last modified February 15 18:19 EST 2012. Contains 205835 sequences.