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A117663 Heptagonal numbers for which the digital root is also a heptagonal number. 0
1, 7, 34, 55, 235, 286, 403, 469, 874, 970, 1177, 1288, 1918, 2059, 2356, 2512, 3367, 3553, 3940, 4141, 5221, 5452, 5929, 6175, 7480, 7756, 8323, 8614, 10144, 10465, 11122, 11458, 13213, 13579, 14326, 14707, 16687, 17098, 17935, 18361, 20566 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..41.

FORMULA

Empirical g.f.: -x*(46*x^8+24*x^7+63*x^6+39*x^5+178*x^4+21*x^3+27*x^2+6*x+1) / ((x-1)^3*(x+1)^2*(x^2+1)^2). - Colin Barker, Jan 17 2014

CROSSREFS

Cf. A000566.

Sequence in context: A001795 A209897 A209814 * A063166 A259055 A195018

Adjacent sequences:  A117660 A117661 A117662 * A117664 A117665 A117666

KEYWORD

nonn,base

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), Apr 11 2006

STATUS

approved

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Last modified February 23 07:42 EST 2018. Contains 299473 sequences. (Running on oeis4.)