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A117104 Sum of two positive heptagonal numbers A000566. 2
2, 8, 14, 19, 25, 35, 36, 41, 52, 56, 62, 68, 73, 82, 88, 89, 99, 110, 113, 115, 119, 130, 136, 146, 149, 155, 162, 166, 167, 182, 190, 193, 196, 203, 207, 223, 224, 229, 236, 242, 244, 253, 260, 269, 270, 287, 290, 293, 296, 301, 304, 316, 320, 337, 341, 343, 347 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

7 is the only prime heptagonal number. Primes which are sums of two positive heptagonal numbers include: {2, 19, 41, 73, 89, 113, 149, 167, 193, 223, 229, 269, 293, 337, 347, 367, 383, ...}.

LINKS

Table of n, a(n) for n=1..57.

FORMULA

{a(n)} = {A000566} + {A000566} = {a*(5*a-3)/2 + b*(5*b-3)/2} \ {A000566}.

CROSSREFS

Cf. A000566, A000040, A000326, A003679, A064826, A117065.

Sequence in context: A160556 A105610 A324691 * A082933 A016933 A294960

Adjacent sequences:  A117101 A117102 A117103 * A117105 A117106 A117107

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Apr 18 2006

EXTENSIONS

Missing 343 added by Giovanni Resta, Jun 15 2016

STATUS

approved

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Last modified October 15 19:25 EDT 2019. Contains 328037 sequences. (Running on oeis4.)