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A191856 First factor in happy factorization of n-th rhombic number. 7
1, 7, 2, 1, 3, 1, 23, 4, 1, 31, 16, 5, 2, 1, 47, 6, 1, 1, 7, 1, 71, 25, 79, 8, 1, 3, 4, 13, 48, 9, 103, 2, 1, 5, 119, 10, 1, 127, 64, 1, 27, 34, 1, 11, 151, 4, 3, 80, 1, 167, 12, 1, 7, 22, 1, 1, 191, 96, 13, 199, 2, 8, 1, 43, 4, 73, 223, 14, 1, 3, 2, 5, 239 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A007966(A007970(n)) = A007970(n) / A191857(n);

(a(n), A191857(n)) is a 2-happy couple;

notation: D in the Conway link.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..99

J. H. Conway, On Happy Factorizations, J. Integer Sequences, Vol. 1, 1998, #1.

PROG

(Haskell)

a191856 = a007966 . a007970  -- Reinhard Zumkeller, Oct 11 2015

CROSSREFS

Cf. A007966, A007970, A191857.

Sequence in context: A197184 A089129 A100957 * A220862 A198229 A133362

Adjacent sequences:  A191853 A191854 A191855 * A191857 A191858 A191859

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 18 2011

EXTENSIONS

Wrong formula removed, thanks to Wolfdieter Lang, who pointed this out. Reinhard Zumkeller, Oct 11 2015

STATUS

approved

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Last modified February 19 18:31 EST 2018. Contains 299356 sequences. (Running on oeis4.)