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 A172009 Count of minimal SNUSP programs using +, -, @ and # to yield N 0
 1, 1, 2, 2, 2, 2, 2, 2, 6, 12, 4, 8, 2, 4, 4, 10, 4, 2, 12, 4, 2, 6, 8, 10, 2, 2, 2, 2, 2, 2, 10, 2, 8, 2, 14, 22, 8, 2, 18, 8, 4, 14, 4, 12, 2, 4, 2, 8, 6, 2, 6, 6, 10, 2, 2, 4, 6, 4, 4, 2, 4, 2, 22, 8, 2, 4, 2, 2, 4, 6, 24, 6, 2, 2, 12, 2, 12, 4, 2, 2, 6, 6, 12, 18, 6, 4, 6, 6, 2, 2, 2, 2, 8, 12, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS SNUSP is a programming language where each command is an individual letter. The four of concern here are +, -, @ and #. + increments the current data value, - decrements it, @ is a "subroutine call" and # is a "return". When an @ is encountered, a record of the location is put on a stack and execution continues. When a # is encountered, if there is a return point on the stack, the execution continues at that a single character beyond that return point. If there is no return point on the stack, execution terminates. Thus "@@++#" would put the first two "@" return points on the stack, increment data twice, return from the second "@" to the last "+", increment the data once more, return from the first "@" to the first "+", increment the data two more times and finally terminate when it hits the "#" with no return points on the stack. The data is always initialized to zero so this effectively puts 5 into the data. In order to place a particular value into the data, there one or more minimal strings of these characters. The i'th element of the sequence gives the number of minimal SNUSP programs using only these characters. After 2, all sequences end in either +++ or @++ both of which are equivalent so that all values above a(2) are even. LINKS EXAMPLE There are 12 minimal programs which yield 10: +@+++++# @@-++++# -@@++++# -@+@+++# +@-@+++# ++@@+++# +@++@++# @@-+@++# -@@+@++# -@+@@++# +@-@@++# ++@@@++# Thus a(10) = 12. PROG (Other) See A172005. CROSSREFS Cf. A172005, A172006, A172007, A172008 Sequence in context: A105255 A140818 A139813 * A299150 A202448 A339165 Adjacent sequences:  A172006 A172007 A172008 * A172010 A172011 A172012 KEYWORD nonn AUTHOR Darrell Plank (jar_czar(AT)msn.com), Jan 22 2010 STATUS approved

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Last modified January 20 00:45 EST 2022. Contains 350467 sequences. (Running on oeis4.)