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A340389
Number at the apex of Recamán's triangle of primes and squares with n rows.
3
0, 3, 9, 59, 1669, 147456, 60924257
OFFSET
1,2
COMMENTS
Form a triangle of n rows and place a distinct prime or square at each position such that (apart from the bottom row) every number is the sum of the two numbers below it, and such that the number at the apex is as small as possible.
REFERENCES
Bernardo Recamán, The Bogotá Puzzles, Dover Publications, 2020, Puzzle 3, p. 3.
LINKS
M. F. Hasler, A340389: Notes and PARI program, OEIS wiki, Aug 2021.
M. F. Hasler, PARI code for A340389 (extracted from the above wiki page), Aug 16 2021.
Sean A. Irvine, Java program (github)
EXAMPLE
n=3:
9
4 5
1 3 2
.
n=4:
59
23 36
16 7 29
13 3 4 25
.
n=5 (B. Mehta):
1669
576 1093
383 193 900
347 36 157 743
324 23 13 144 599
.
n=6 (_Sean A. Irvine): _
147456
63487 83969
33211 30276 53693
17424 15787 14489 39204
10853 6571 9216 5273 33931
10529 324 6247 2969 2304 31627
.
From Bert Dobbelaere, May 11 2021: (Start)
n=7:
60924257
21861757 39062500
7799257 14062500 25000000
2736757 5062500 9000000 16000000
914257 1822500 3240000 5760000 10240000
258157 656100 1166400 2073600 3686400 6553600
21961 236196 419904 746496 1327104 2359296 4194304
(End)
PROG
(PARI) see LINKS
CROSSREFS
Cf. A089237 (primes and squares).
Sequence in context: A105466 A261244 A018504 * A140812 A202210 A243425
KEYWORD
nonn,hard,more
AUTHOR
Sean A. Irvine, Apr 24 2021
EXTENSIONS
a(7) from Bert Dobbelaere, May 11 2021
STATUS
approved