Truncatable (left and right side; any number of truncated digits allowed) decimal primes,whose sum of digits is square
Alexander Povolotsky
apovolot at gmail.com
Tue Dec 25 18:14:56 CET 2007
Dear SeqFans,
Here are the three terms of the potential sequence of truncatable
(left and right side; any number of truncated digits allowed) decimal
primes, whose sum of digits (in decimal form) is square:
5375937799, 3953759377999393, 9539537593779993937
a(1)=5375937799 because it arises from truncating a(2) and
5 + 3 + 7 + 5 + 9 + 3 + 7 + 7 + 9 + 9 = 64
a(2)=3953759377999393 because it arises from truncating a(3) and
3 + 9 + 5 + 3 + 7 + 5 + 9 + 3 + 7 + 7 + 9 + 9 + 9 + 3 + 9 + 3 = 100
a(3)=9539537593779993937 because
9 + 5 + 3 + 9 + 5 + 3 + 7 + 5 + 9 + 3 + 7 + 7 + 9 + 9 + 9 + 3 + 9 + 3 + 7 = 121
Is this sequence finite (hope not) ?
Are there similar sequences ?
Regards,
Alex
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